lgarbz Posted April 17, 2015 Report Share Posted April 17, 2015 Hey,The forum wouldn't let me post in the HVAC section, so i'm posting it here.I have a 88 conquest with automatic HVAC.I've got a thread in the restoration center under "Conquest Project." I need a little help/advise. My HVAC head unit does not illuminate.The buttons beep when you press them, but the blower motor does not turn on. I have not tested the blower motor with my power probe yet, but that will be the next step. Any thoughts on why the head unit beeps but the leds do not light up? Also found this wire under the passenger side dash when I was messing with stuff.It is not plugged in to anything. Any Idea where it goes? http://i1148.photobucket.com/albums/o563/lgarbz/IMG_0684_zps0du50hn0.jpg http://i1148.photobucket.com/albums/o563/lgarbz/IMG_0685_zpstizd3nmq.jpg Thanks in advance! Link to comment Share on other sites More sharing options...
BuGG Posted April 17, 2015 Report Share Posted April 17, 2015 That's a temp sensor and it slides in a slot under the passenger foot well cover. The cover thats below the glove box. Link to comment Share on other sites More sharing options...
lgarbz Posted April 17, 2015 Author Report Share Posted April 17, 2015 Thank you.Any ideas on the rest? Link to comment Share on other sites More sharing options...
Turbo Cary Posted April 17, 2015 Report Share Posted April 17, 2015 My friend had the same issue and said it was a fuse. Check those and see if any are trashed. Link to comment Share on other sites More sharing options...
lgarbz Posted April 17, 2015 Author Report Share Posted April 17, 2015 I checked the 20a fuse. and the A/C fuse. Are there other fuses or fusible links somewhere other than the fuse block under the driver side dash? Link to comment Share on other sites More sharing options...
Turbo Cary Posted April 17, 2015 Report Share Posted April 17, 2015 No but I would recheck them all. Maybe swap another 20a fuse to make sure the contact points aren't corroded. If you can get a multimeter and check voltage at the connector for the a/c controls. Link to comment Share on other sites More sharing options...
lgarbz Posted April 17, 2015 Author Report Share Posted April 17, 2015 Just went out to tinker with it. The head unit is lighting up and the blower motor works. Maybe because I took out the fuse and plugged it back in earlier, or I might have a bad ground somewhere. Blower motor only works on one speed so I need a new resistor. Foot/Face/Defrost mode is inop. what controls the foot/face actuator? I know there's a vacuum tank at the front of the engine bay, but the vacuum line is not plugged in to engine vacuum anywhere. Where is it supposed to plug in? Link to comment Share on other sites More sharing options...
nightwalkerancestery Posted April 17, 2015 Report Share Posted April 17, 2015 Okay, do this. The issue you're having is with the fuse. The HVAC units produce quite a bit of heat on the electrical system from the blower motor. Heat makes metal expand. This expansion in the HVAC electrical system primarily occurs right at that fuse. It'll expand, but once it cools down it contracts and over time it can contract to the point where the blade of the fuse doesn't have enough contact with the high current side of the fuse panel. When you reseated the fuse, it got better contact with the fuse panel. But, over time you'll have the same issue within only a few times running the HVAC. There's an easy fix. Just take a small jewellers screw driver and bend the terminals in the fuse panel so the fuse will fit more snug. Problem solved! Since you'll be down there, May as well do all the fuse terminals - Charles Link to comment Share on other sites More sharing options...
lgarbz Posted April 17, 2015 Author Report Share Posted April 17, 2015 Thanks for the tip. I'll try that next time I'm out working on it. Link to comment Share on other sites More sharing options...
mikec Posted April 17, 2015 Report Share Posted April 17, 2015 Dash vent actuators get vacuum from a black reservoir mounted next to the ABS actuator. There are several vacuum lines in that area as well as a couple small white plastic gizmos that look like hose couplers... they're one-way valves. They allow airflow towards the engine (i.e. let vacuum get created in the reservoir) and block turbo boost pressure. Follow the hoses, you'll see two white check valves and a few T connectors. One hose should dive down the firewall to a small copper pipe sticking through the same firewall hole as the air conditioning refrigerant lines - this copper pipe then feeds the dash vents. Other sides of the T work their way behind the engine to the intake manifold. On the side of the throttle body you'll see a row of three vac ports and another port about an inch or two lower. That lower port feeds the dash vents and reservoir and also powers the cruise control. The cruise control has a separate vacuum pump to generate vacuum during boost operation; that pump is mounted next to the driver side headlight on 88 cars. The pump runs only when the cruise control is ON and boost pressure is present - it doesn't run all the time. One of those little white check valves isolates this vacuum pump from the dash vent reservoir & hoses too so the pump can't/won't run the dash vents. The various speeds of the interior fan motor are controlled by a Darlington pair style transistor. it's mounted to the bottom of the fan box, mashed up against the firewall so it's almost impossible to get to without taking out the whole fan box. Look for a 4-wire connector near the fan motor, that might be your only problem. MAX fan speed is triggered by a separate relay that bypasses this transistor which is what is allowing your fan to run at that speed. If you remove the ash tray and look straight in you'll see a couple of vacuum switching solenoids and a wad of vac hoses. Those solenoids are what control the face/foot/defrost/recirculate actuators. There are 3 actuators:* fresh air/recirculate actuator on passenger side of car, behind the glove box and next to the air intake for recirculate air.* defrost actuator. This is mounted vertically on the driver side of the heater core assembly, close to the firewall.* face/foot/bled actuator. This is mounted horizontally to the side of the heater core assembly. It has two vac hoses feeding it: one selects FACE vents, one selects FOOT vents, and applying vacuum to both splits the airflow between FACE and FOOT ("BLEND" as Mitsu calls it). This actuator includes a rubber bellows over the pushrod... and this bellows commonly splits/tears leading to a big vacuum leak. If your face/foot/blend function doesn't work right odds are the bellows is shot. The actuator is no longer available from Mitsu. Options are to find a way to put a new rubber shell over the busted bellows (imagine coating the bellows with a baloon), replacing the actuator with a defrost style one and giving up the BLEND operation, or finding a good used actuator. mike c. Link to comment Share on other sites More sharing options...
tankbob Posted April 17, 2015 Report Share Posted April 17, 2015 Cant hurt to check the fusible link for the heater, its located behind the panel next to your battery. Link to comment Share on other sites More sharing options...
87redcat Posted April 17, 2015 Report Share Posted April 17, 2015 Check out the "heat and ac" thread. mike c and kev have some good write ups on your exact questions. and if I'm correct kev shows you how to use a single actuator to replace the dual. Link to comment Share on other sites More sharing options...
importwarrior Posted April 17, 2015 Report Share Posted April 17, 2015 here is some good reading kind of long but very informative http://www.starquestclub.com/forum/index.php?showtopic=145039 Also readhttp://www.starquestclub.com/forum/index.php?showtopic=131748 Link to comment Share on other sites More sharing options...
BOHO Posted April 17, 2015 Report Share Posted April 17, 2015 Got dangit....I love me some mikec posts...always hit me in the right spot. Link to comment Share on other sites More sharing options...
pcristquester Posted April 17, 2015 Report Share Posted April 17, 2015 ^^^^^^ x 100 Link to comment Share on other sites More sharing options...
nightwalkerancestery Posted April 17, 2015 Report Share Posted April 17, 2015 (edited) Thanks for the tip. I'll try that next time I'm out working on it. The reason I mentioned this is because with your exact problem and what you did to "solve" it matches EXACTLY what has happened on both of my cars. The unit beeps, but there's no display, the actuators work in opening the door, But the fan doesn't blow. The first time it happened was on the car I was restoring. All new and rebuilt. I traced all the wires finding nothing wrong. Finally, I checked the fuse and forgot to turn the key off. As soon as I touched it it turned on. Just bent those contacts and not a problem since in both cars. As to your face/foot issue, like was already said the bellows rot and tear on them. I'm actually in the process of getting a replacement boot from something else. I may have something that will work in sealing back up that lower half. But haven't gotten around to it. The boot on the door lock actuator looks close to the same size. I have a bad spare that I've been meaning to try on the blend actuator. I'll let people know if this works! - Charles Edited April 17, 2015 by nightwalkerancestery 1 Link to comment Share on other sites More sharing options...
pcristquester Posted April 17, 2015 Report Share Posted April 17, 2015 Another option on the foot/face actuator issue,if you are in a warmer climate area like I am is to basically mechanically disable the actuator (I removed the spring) so no more air flows to the foot area. Easily reversible if I wanted. I rarely (almost never) use the heat anyways, so I want full flow to the dash vents for AC. Black on black with leather here in so cal= automatic heat Link to comment Share on other sites More sharing options...
lgarbz Posted April 18, 2015 Author Report Share Posted April 18, 2015 Got the majority of the HVAC stuff figured out. Found that my vacuum tank was not hooked up to engine vacuum, Plugged it in, problem solved. Have a video of the HVAC unit running and a quick start up/walk around in my thread in the restoration center. Thanks for all the help guys! Link to comment Share on other sites More sharing options...
G54Bstore Posted July 3, 2015 Report Share Posted July 3, 2015 Another option on the foot/face actuator issue,if you are in a warmer climate area like I am is to basically mechanically disable the actuator (I removed the spring) so no more air flows to the foot area. Easily reversible if I wanted. I rarely (almost never) use the heat anyways, so I want full flow to the dash vents for AC. Black on black with leather here in so cal= automatic heatThat's what I did man . Got cold air blowing out the dash vents now. It's nice. Link to comment Share on other sites More sharing options...
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