BaltTSI Posted June 1, 2008 Report Share Posted June 1, 2008 My AC system had been changed over to the new R-134a when I bought it, but I ended up changing the compressor out for a used one because of a bad clutch, after getting it charged up it lasted a whole summer, but it must have a small leak because it's dead now. I had a can of R-134a sitting around that came with it's own gauge that tells you where your pressure is at when you hook it up, indicating if your good low hi or whatever, well it says mine is reading real high, it goes to the "red" part of the gauge and that means you could have mechanical trouble and don't try to charge it. I'm totally clueless about AC systems, how would you be getting a high reading from a system that doesn't work? and yes, I'm hooking it up to the right connector, it only fits the low pressure one. Link to comment Share on other sites More sharing options...
thegrapest Posted June 1, 2008 Report Share Posted June 1, 2008 My AC system had been changed over to the new R-134a when I bought it, but I ended up changing the compressor out for a used one because of a bad clutch, after getting it charged up it lasted a whole summer, but it must have a small leak because it's dead now. I had a can of R-134a sitting around that came with it's own gauge that tells you where your pressure is at when you hook it up, indicating if your good low hi or whatever, well it says mine is reading real high, it goes to the "red" part of the gauge and that means you could have mechanical trouble and don't try to charge it. I'm totally clueless about AC systems, how would you be getting a high reading from a system that doesn't work? and yes, I'm hooking it up to the right connector, it only fits the low pressure one. Actually I am having the exact problem, I had my lines off so I know that it is empty but when I try to charge it mine reads in the red also Link to comment Share on other sites More sharing options...
BaltTSI Posted June 2, 2008 Author Report Share Posted June 2, 2008 Hummmm, well I hope someone can fill us in on what's going on :confused0024: Link to comment Share on other sites More sharing options...
Dcrasta Posted June 2, 2008 Report Share Posted June 2, 2008 Dont you have to vacuum it down first so there is like - or 0 pressure? Take it to a shop Link to comment Share on other sites More sharing options...
JAinsworth Posted June 2, 2008 Report Share Posted June 2, 2008 Dont you have to vacuum it down first so there is like - or 0 pressure? Take it to a shop I was thinking the same thing but I'm no a/c expert by far. Jimmy Link to comment Share on other sites More sharing options...
John86TSi Posted June 2, 2008 Report Share Posted June 2, 2008 Hey Balt! I have not changed any of my starquests over to R134A yet, mainly because I don't have the gages for that freon and I still have some R12 left over from my a/c days. I do have to change out a front seal on my compressor on the 86, and mitsubishiparts.com has an entire seal kit for the compressor for $30 or so. I have not replaced a front seal on these compressors yet, but looking at the parts manual it looks pretty easy if you have the seal kit. If you take a compressor off of the car or remove and replace the drier, try to seal up the open hoses with plastic bags and tape to minimize the introduction of air (and the real culprit - humidity) into the system until you are ready to replace the part. Regular air and moisture will prevent your system from working correctly! Also, if the part has o-rings, replace them, otherwise they will leak. After the repair and with the compressor back on (and some "compatible to specific refrigerant" oil replaced for what you drained out), you definitely have to vacuum down the system to get all the air and moisture out of the system, especially from the drier. Some people "flow" refrigerant through the system and let it go out the high side to eliminate the moisture, but that will not get rid of all of it. With a good vacuum, you bring out the moisture from the dessicant within the drier and remove it. The drier is the unit that has the sight glass on top of it in the front of the car in front of the radiator on the left hand side. If you have had the system open for a length of time (and did not seal the hoses) it might be full of moisture and it would be easier to replace it. Advance auto parts has them for a reasonable price (20 to 30 dollars). If you have had it open for a long time and dirt has worked its way into the lines, all bets are off and you have more problems than I would want to work with. ) Once a good vacuum has been maintained (I let it run for a good while) and checked for leaks, you "break" the vacuum with the refrigerant and let it charge to a positive pressure (above the pressure switches actuation pressure installed near the drier). One could also "jump" the plug there that would allow the compressor clutch to come on, and that way the suction of the compressor allows more refrigerant to go in. OR, just turn on your a/c control inside the car to the maximum while charging, and roll up the windows. Once the pressure rises above the switch pressure setting, the compressor clutch will come on (if all else with the car is good). With the sight glass, it is easy... just charge slowly till all the bubbles disappear from the sight glass while the system is running (I use a flashlight to see the bubbles go by). Let the system stabilize and cool the interior down, and recheck for bubbles again. Once the bubbles are gone, you can add just a touch more freon, but not much!!! From this point on, the more freon you add, the worse your system will operate, and the evaporator temperature will rise with additional freon. Your system will start running warmer instead of cooler. Too much freon, and your high side will start to try to stall the compressor and bad things will result! I hope this short course will help you and others out. If you have any other questions, feel free to ask. John86TSi Link to comment Share on other sites More sharing options...
craig87 Posted June 2, 2008 Report Share Posted June 2, 2008 Its been a while since I did a retro-fit but sight glass charging would be a bad idea r134 should have a 10% undercharge to work properly. as far as what the guage reading says sitting with a 134a chargein in it at rest pressure should be pretty close to ambiant temp. my suggestion would be to take it somewhere that would throw it on the machine around here a basic ac check will be about 40bux. As a common courtesy show the guy what you dumped in it from a can. those cans with sealer screw with the filters in the ac machine and extra precautions must be taken. Link to comment Share on other sites More sharing options...
BaltTSI Posted June 2, 2008 Author Report Share Posted June 2, 2008 Good info John! but my compressor isn't even engaging, I hook up the bottle of R-134 and it won't even go in, the pressure needle just points to the red (high pressure) I guess it's too high to flow? like I said, it was working for at least one season, nothing has been opened since then, after I put the compressor on I had a shop charge it up, he didn't think it was going to work because all I was getting done was a charge, but it did...for a while. Could I just apply power to the power wire going to the clutch to get it to engage, would that allow the refrigerant to flow in? or it's just too high to take it? Link to comment Share on other sites More sharing options...
Whiplash Posted June 2, 2008 Report Share Posted June 2, 2008 When the A/C system is not running the low side will read high. After the compressor kicks in the low side drops, and the high side gos up. Near the dryer there is a switch. Pull the plug and jump a wire from one side to the other. Did the system come on? Link to comment Share on other sites More sharing options...
Shelby Posted June 2, 2008 Report Share Posted June 2, 2008 this is because the can hose is not opening the valve in the line fiting,, all your reading is the cans pressure , to retrofit r134 you have to change the line charge fitings,,this can get very complicate'd as i have found 5 or 6 diff retrofit adaptors some don't work very well,, most require you to remove the schrader valve in the oem line others do not , i'd also sugest you use a reg a/c charge ing manifold set with proper gauges to do the rechargeing and testing , the low side will tell you nothing about what the high side pressures actualy are,, and thats what you need to pay attention to the oil use'd in the r12 system is not compatiable with r134a oil,, if your useing the r12 compressor you'l need to change out the oil with an oil compatiable with both r12 and r134 , the oil that they give you in the retro kit will not work in a system that has had r12 in it,, silly people know that but they don't care Link to comment Share on other sites More sharing options...
mikec Posted June 3, 2008 Report Share Posted June 3, 2008 What is the actual pressure reading on the guage? "Red" is pretty meaningless. Topping off an a/c system is always done on the SUCTION side port of the compressor. That'll be the one that does NOT get hot when the compressor is running; it's also the larger hose (not fitting) going to/from the compressor. The compressor needs to be running too unless the system is totally empty and has been connected to a vacuum pump to evacuate it. Then the "first can" of recharge will flow into the system from the pressure in the can itself. When a system is converted to R-134, the compressor fittings are supposed to be replaced. Or at least have special adaptors screwed into them... the NEW fittings are different sizes compared to R-12 to make sure folks don't accidentally connect the wrong type of refrigerant tanks to the car during a re-charge. If your car doesn't have these fittings you might be connecting to the wrong compressor port. If your R-134 recharge can starts getting WARMER then you definately have it backwards - the recharge can should get ice cold as it empties into your car. Sticking the can into a pan of warm/hot (not boiling!) water will help get more refrigerant out of the can and into your car. Once the can is half-empty (or more) stick it in a pan to heat it up... that raises the refrigerant pressure in the can so it can force itself into the car. mike c. Link to comment Share on other sites More sharing options...
Mech Posted June 3, 2008 Report Share Posted June 3, 2008 Ay my shop we have both a 134a machine and r-12 machine. So I dont have any experience with filling with cans or whatever. Applying vacuum serves a few purposes. one is to eliminate moisture from the system. another is to check for leaks( apply vaccum, let it sit for awhile and see if it it losses vacuum) if it drops quickly, you have a gross leak.) Having vacuum in the system does help a bit when you are charging with R-12 too, with the initial charge. With 134a, you charge the HIGH side (Discharge) with the car OFF, filling the entire amount before you start the car. With r-12, you run the car and slowly fill the LOW side (suction) with the climate control on A/C. If you have a machine, its easy because you can exactly measure how much freon goes in. You can also go by the sight glass on the filter/dryer. Its usually pretty accurate. You fill until you don't see any more bubbles. I've compared both with the machine and the the sight glass. The sight glass is usually accurate. Link to comment Share on other sites More sharing options...
Shelby Posted June 3, 2008 Report Share Posted June 3, 2008 not sure i ever saw a r14 system with a sight glass,, but he was useing a charge it your self can,with an empty system,, so that tells you the valve into the system was not being open'd , been there done that,, the internal valve must be reomve'd from the oem charge fiting and the new charge cap install'd , some have a rod or pin that is supose'd to push open the oem valve but 90% of the time they don't reach so the internal valve must be remove'd and you have to rely on the adaptor seal working if it has one,,if it does not then you'l need to get a diff adaptor,, by the way BOTH fitings have to have r134 adaptor caps on them by law and a sticker place'd on the under hood saysing it's a retrofit quest charge is 2 lbs r12 so that means aprox 28 oz of r134 is need'd auto zone and advance adaptor fitings suck try car quest or napa for good adaptors Link to comment Share on other sites More sharing options...
BaltTSI Posted June 3, 2008 Author Report Share Posted June 3, 2008 The gauge on the can goes from zero to about 70 (thats the red zone on the gauge) so it is reading, the compressor has the retro fit valves on it from the old compressor, there was a sticker under the hood saying that the system had been changed to 134 when I bought the car. Link to comment Share on other sites More sharing options...
Jehu Posted June 3, 2008 Report Share Posted June 3, 2008 I'm going through a retrofit here. Reading up on it now. The problems I've seen that are similar to yours come from moisture and cross contanimation of the different mixtures. You're probably going to need a total evacuation done from a shop. I'm looking into getting this done myself... Link to comment Share on other sites More sharing options...
BaltTSI Posted June 3, 2008 Author Report Share Posted June 3, 2008 Yeah, I guess I'll end up doing that, it's getting hot around here! Link to comment Share on other sites More sharing options...
John86TSi Posted June 4, 2008 Report Share Posted June 4, 2008 Balt: I thought I was clear in my long post to you that I was dealing with R12, and not R134A. The sight glass IS accurate for R12 freon when the system is operating properly. I think Shelby nailed it right when he said that your adapter fittings are not allowing your can of R134 to enter the compressor suction line. Also, there is less of a charge needed with R134 as was stated, and the sight glass probably is not accurate for the R134A. For a good changeover, the old R12 compatible oil needs to be removed from the compressor, drier, and the rest of the system. The driers are cheap at Advance auto parts, it is probably a good thing to just change it out and be done with it instead of trying to get all of the old oil out of it. It is hard to flush all of the old oil out of the lines, usually the best you can do is the best you can do. I don't have the overall oil charge for our system, maybe Shelby has gotten that over the years and has that handy. There are three sizes of o-rings with our system. MB946604 total qty of 4 in our system $2.38 ea MR114744 total qty of 3 in our system $0.52 ea MB946605 total qty of 2 in our system $1.74 ea these are the new, updated part numbers for our old numbers. Mitsubishiparts.com prices The compressor complete seal kit (including the front compressor seal) is MB276079 $30.84 ea When you get it running, post again and let us know what had to be done to your system to get it running. BTW, there are two pressure switches by the drier. On my 86, the smaller connector (white) with side by side pins, when shorted, brings on the secondary fan and the pusher fan. The larger black connector, when shorted, brings in the magnetic clutch on the compressor IF the engine coolant switch (with the yellow/white wire) is grounded because of the engine being warmed up! Cold engine, or bad coolant switch, then there is no compressor clutch engagement. Sure hope this info helps someone out............ John86TSi Link to comment Share on other sites More sharing options...
mikec Posted June 4, 2008 Report Share Posted June 4, 2008 60 to 70psi on a system that is OFF sounds about right, going from what I remember seeing on my car. Mine is R-134 converted. What I would do is: 1: connect the refrigerant can to the compressor suction port. Don't open the control valve on the can yet... 2: start the engine and turn the a/c on to 65 deg, fan at MAX. 3: rev the engine for a minute so the compressor actually does something with whatever refrigerant is left in your car. 4: What does the pressure guage on the can read now? Hopefully it is much lower. Open the valve if needed to get the gauge to read. Let refrigerant flow into the system, watching the site glass. You don't want it fully cleared up. Ideally you'd have 2 pressure guages like the a/c shops use... monitoring the compressor input and output pressures. That really lets you know when you've got the right amount of refrigerant added. mike c. Link to comment Share on other sites More sharing options...
marso Posted June 4, 2008 Report Share Posted June 4, 2008 (edited) I agree that a complete switch would be the most beneficial but the notion that the oils in R-12 and R-134 are not compatible is false. Refrigerant companies said that when the change first started to make everyone change their systems so they could make money. I have changed every car I've owned to 134 without completely flushing and they work fine. My A/C blows around 43' on full cold setting. You must change the drier and pull 30hg for at least an hour. If you did open up the lines definately change the orings. If you did not drain the compressor do not put in an oil charge. If you do there will be too much oil in the system causing the oriface to blow too much oil with the refrigerant so it will not cool properly. Most cans come with oil in them already. Another thing I don't like to use is leak detector in the refrigerant. It's just something else that shouldn't be in the mix when the heat exchange occurs. Leak detector is used to find a leak of an existing system then it's dumped after the leak is fixed, flushed, vacuumed and refilled. I charge by thermometer in the middle vent system on high. Put a charge in the system by guage temperature then look at the thermometer. You can fine tune the system by having someone let refrigerant in while you watch the thermometer. When the system starts to have too much the temp will rise. Let it settle then bleed a little off until the temp drops. I know your suppose to recover it but most car owners don't have one or know how to use it. If you really want your car to blow colder than anything else use a refrigerant called Hot Shot. It's a blend of different refrigerants. The only problem is if you have a leak you must dump the whole system because they vent at different rates so the mix won't stay the same. Shelby is right. The fittings never fit correctly and there are different ones. I have found if you tighten the low side down too much it locks the two pins together so it won't push in. Put some blue lock tite on it before you reinstall it and push the pin in while you install it. you will feel the pin trying to push back when it's down too far. Notice I've been saying refrigerant not Freon. Freon is a brand name of a refrigerant. Not many cars have it in them unless the manufacturer had a contract with that company. Hope some of this helps. Edited June 4, 2008 by marso Link to comment Share on other sites More sharing options...
Shelby Posted June 4, 2008 Report Share Posted June 4, 2008 you'l find 3 commanly use'd compressor oils,, i'd sugest you get a little of each and try mixing them your self 2 will mix the 3'd will not,,, pac oil will not mix with r12 refergerant oil Link to comment Share on other sites More sharing options...
naughty_auty Posted June 24, 2008 Report Share Posted June 24, 2008 great read balt if you still messin with it make sure you pump is on while trying to fill it sound like the pump is not on just use a jummper wire on the low pressure switch to turn on the pump and fill away I do have a question about this If you have a shop evac the system can you fill it up with r134 or is there somthing else that needs to be done besides checking for leaks and replacing worn parts Link to comment Share on other sites More sharing options...
BaltTSI Posted June 25, 2008 Author Report Share Posted June 25, 2008 I'm not getting e-mail notifications on any of my posts anymore for some reason so I thought this was a done deal, until I noticed it back in the top 10 when I was checking another post of mine, I'll try some of these ideas when I get my new thermo sensor in for the fans. Link to comment Share on other sites More sharing options...
Shelby Posted June 26, 2008 Report Share Posted June 26, 2008 how much R134 are you guys puting in,,, last time i look'd it up if i recall it right it was 26-28 oz r134 Link to comment Share on other sites More sharing options...
Vnomous1 Posted June 26, 2008 Report Share Posted June 26, 2008 Just a thought... Are your relays working properly? I thought I had the same issue...tapped on the relays and wa-lah, the compressor engaged. So I cleaned the connectors and ensured a good ground. it has been working ever since. However, you may have a a pressure switch issue. Try looping/bridging the presuure switch connector to see if the compressor will engage, if so, you have isolated the problem. DO NOT leave the connector bridged, this will cause the system to run continuously, building excessive pressure and you will pop a hose. Everything else I have read in the responses seem to be accurate. Link to comment Share on other sites More sharing options...
naughty_auty Posted June 26, 2008 Report Share Posted June 26, 2008 In my read on this is that the system is empty and if it's empty it will not turn on at all so jumping the low pressure swith plug with a whire will turn the pump on and the pressure gauge will drop on the filler can to zero till it starts to build pressure. Just jump the plug and tell us if it turns on the pump Link to comment Share on other sites More sharing options...
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