no heat

[craigk]

Has anyone else had trouble with their heater? Some time this summer, the heat quit working. I put it in Auto mode and turn the temp up above the outside air temp and I can't get any heat to come out. I can turn the setting down and get A/C. I crawled under the dash and felt the bypass tube coming through the firewall and it felt plenty warm, so I'm tempted to rule out a blocked heater core. I disconnected the mixing door control arm and tried it at both ends of it's travel and it made no difference. I have not been able to find a setting that causes said mixing door actuator to move either. I was wondering if the temperature sensor could be bad? But it seems that moving the mixing door(if that's what I think I was playing with on the passenger side) would override any effect that a bad temp sensor would have. My service manual only suggests a blocked heater core. I was thinking of flushing the cooling system and making sure nothing was wrong there just in case. Any feedback would be very welcome.

[cocacola08]

Just a guess here:

You set it above the outside temp, but was it above the temp inside the car?

A suggestion:

Turn the a/c (without hitting low/med/high so its totally auto) way down cold, then slowly push it up. As the temp you set up to goes up the slower the air should come out, once the set temp meets the air temp in the car, the fan should slow way down or stop blowing. That'll show you the inside temp. If you go above that point it would in theory start blowing warm air

[craigk]

I'm going to try your suggestion. The inside air in the am is very cold, so I have already tried that by default. But it sounds like a good idea and could help in my investigation, thanks.

[wawazat??]

CraigK,
First of all, I want to welcome you to the club. I see you recently joined and am sorry to say that last weekend you missed a mini-meet at the Chili's on Washtenaw in A2. Four people, two SVX's (SVX10 & Mr. Pockets), mine is back from the body shop tomorrow.

On the heater issue, I recently replaced the t-stat, cap, and upper and lower hoses after my car had a minor overheat. While flushing and refilling the system I noticed that I did not get heta into the cockpit when the radiator and overflow reservoir where not up to the full marks. Once the system was filled, everything was fine. It was very strange. Obviously your fan works if the AC was blowing. Is there a second door/flap that admits incoming air to the heater core from the blower. I wonder if the heater core is in a separate chamber within the ductwork. I'll look at my service manuals and see if anything jumps out to me. Good luck!

[dromano]

I'm learning on this one. At age 60 I would never try to heat by using auto. To me auto means the compressor is running for heat or cool. If I want heat I set the temp in econ mode and the appropriate fan speed. What happens in defrost mode? Can you get heat to the windshield?
David

[craigk]

I did some more investigation last night. The bypass tube passing through the firewall is very hot, so I'm getting more convinced there is hot H2O available. I've tried every setting I can and I get absolutely no heat. I also cannot find a setting that causes the actuator on the bottom of the system on the passenger side to move. Moving it manually still doesn't help. I tried the suggested experiment of turning the temp down to activate the A/C, it does, and then turning it up until the fan slows down and the system starts making heat. What I found was that the fan never slows down but some actuators do move. Is there a more indepth diagnostic manual available for this system? I would bet by checking certain behaviors, the exact sensor or whatever could be pinpointed. The local dealer I talked to said it could easily be over a $1000 if they have to remove the dash. For a car with over a 150k, that's not going to work.

[cocacola08]

Well, now you've got me beat

Good luck.

Did you try some of the things the other guys said?

[LarryIII]

Craig,


Just a thought to run a test to narrow down the possible culprits.

Put the setting on the defrost mode and set the temp as high as you can. See if you get hot/dry air from the vents by the base of the windshield. If you do, something is screwed up with the mixing flaps for heat on the feet. If you don't, it could be your temp sensor or temp setting control. Good Luck.

Larry III

[Mr. Pockets]

Originally posted by craigk
I did some more investigation last night. The bypass tube passing through the firewall is very hot, so I'm getting more convinced there is hot H2O available. I've tried every setting I can and I get absolutely no heat. I also cannot find a setting that causes the actuator on the bottom of the system on the passenger side to move. Moving it manually still doesn't help. I tried the suggested experiment of turning the temp down to activate the A/C, it does, and then turning it up until the fan slows down and the system starts making heat. What I found was that the fan never slows down but some actuators do move. Is there a more indepth diagnostic manual available for this system? I would bet by checking certain behaviors, the exact sensor or whatever could be pinpointed. The local dealer I talked to said it could easily be over a $1000 if they have to remove the dash. For a car with over a 150k, that's not going to work.

Craig, welcome to the site! Are you getting heat out of the floor vents, or just not at all? Hot air is not supposed to come out of the dash vents, only the floor. As I understand it, that's so hot air isn't blowing into your face, drying your eyes out. How thoughtful. :)

What year / color is your SVX? I see a few around town, but very rarely. Yesterday I saw a black over claret with no spoiler. A few weeks ago I saw a blue. Once in a great while I see a '94-'97 red. And every few weeks I see a black over pearl in Ypsi but I never have windshield notes with me. I have talked to the owner once, but I wrote out the url wrongo n the note I gave him. Doh!

[craigk]

I get absolutely no heat at any location. I seem to remember that the fan speed would lower once temperature was reached as suggested by one of the other members. Since I can't duplicate that behavior, I'm beginning to think there is a temp sensor problem. Which couild only mean that the A/C is re-cooling my hot air or there is some other flap or valve inside which is not working.

My black SVX, 92', is mostly driven by my wife. It doesn't have a wing and the trunk lid has a crunched part where she backed into something. Mostly the car can be recognized form the license plate, RALYCAR. Which was transferred from my RX7 rally car that I used to compete with. Being a 92' with 150k, I've given up trying to keep it too nice. In another 50k miles it's going to need a new tranny after all, which would probably be worth more than the vehicle by that point.