jobberone

Changed thermostat as thought that was problem but although it probably was bad I'm now dead on 190 degrees and still no heat. Doesn't matter whether on auto or manual. I did have heat ONE day about two months ago, so I thinking a stuck or bad servo.

I did change over from R12 to R134 with new compressor, orifice tube, and drier and I don't have A/C either. However, I'm going to leak it down and recheck vacuum leakdown on that again before recharging.

So is this a simple fix/check or do I have to go to the doctor? :confused:

rick lambert

My guess would be stuck servo :rolleyes: But I'd also like to know how much for the new compressor and change over-I need to do that :seeya

bogus

under the left headlite is a vacuum canister. check to be 100% sure that the little vacuum hose is connected.

pablocruise

Let me recommend you look in the archives. Lots of excellent threads on this there. Look on the left of this screen by your name. above "community" is "search". Click it, then type "No heat" in the search field, then see where it says "recent topics"? Change it to archived topics. Then go lower and choose "C4 tech" leave the "author" blank.
There is a web page by Idaho corvettes that has all the codes listed. You can go to your controller and extract yours if any. Do all the mechanical checks on the system. My bet is this:
http://forums.corvetteforum.com/zerothread?id=202649
Let me know if need more assistance

jobberone

call (321) 624-1374 and speak to Wayne at C V Axles and Air. They are great to work with and can get you a compressor at a great price. Get the drier and they often will throw in the orifice tube with it. BTW, be sure to use the green or R134 compliant o-rings when you change them out, change every flipping one, and make sure you put four on the compressor connection (I left two off as did the last person who did that job). Fill the drier with 2 oz of oil as well. Check the vacuum for at least 30 minutes and each fitting with soapy water. I'm sure you know all this but for those of us doing it for the first time this may save a few hours of headaches. Best. PM me if you want.

jobberone

For some reason I can't get search to work on my computer. While typing this I just realized I have no cookies on. I'll make the adjustments and see what happens and thanks.

jobberone

You were right. Someone had broken the vacuum tubing at the throttle body. I found that changing the thermostat. While working on it after fixing A/C I traced it to the vacuum canister. DUH. Thanks. However that hasn't fixed the heat problem so do you have anymore great ideas. How do I test the control unit? Thanks again.


[Modified by jobberone, 11:31 AM 3/13/2004]

84whitevette

Did you change the coolant? You may possibly have air trapped in the heater core.

Pete.

Just re-read your post... You changed the thermostat, so you probably put fresh coolant in. I would suspect air trapping as a possible cause. Some say if you lift the front end of the car (so radiator opening is highest point) and open the radiator cap (with engine cold) and then let the engine run at about 2,000 rpm. Once warm and the thermostat is open, then fill if needed. This should help purge the air, if its the cause.

Pete.


[Modified by 84whitevette, 12:36 AM 3/13/2004]


[Modified by 84whitevette, 12:37 AM 3/13/2004]

jobberone

Can I fix this by pressure checking the radiator and hoses?

84whitevette

I'm not sure if that would work. In my other chevy's they would always air trap. I just acquired this vette, so I'm about to service the cooling system in a few weeks... I'm sure i'll run into the same issue.

HeeHaw89

Do you have the C68 elec heat/air or manual style. If you have the C68 you may have a more invlolved problem.

jobberone

it's the elect/auto controller and not the manual one. What could the problem be?

jobberone

Great. I'll try that. Thanks again.

GRX

Did you check for vacuum REACHING the valve?????

pablocruise

Yeah, check the vac source. It comes off a 90* angle rubber boot off the back of the intake upper plennum and goes into very brittle plastic tubing that cracks easily:


From there it goes to the circuit board controller

IF and that's a big if, the controller's solder isn't loose, it should send the vac to this door:

Sometimes the plastic clip (circled in yellow) breaks and the actuator rod will move past the door.
Check the door's operation of moving back and forth by having the engine running(to provide vacuum) or after immediately turning off the engine while there is still abit of vac left in the system. Get into the passenger footwell and listen for the door moving as you switch the heat on at the dash controls. Or remove this controller and look down into the cavity:

If want to manually check the movement of the door, insert a long skinny antenna or someting and see if you can gently move the door back and forth. You shouldn't be able to. If it's loose and flaps back and forth easliy, the clip is broken.
If all those things are OK, then check the solder and resistors on the circuit board. Go back up to my previous response above in this thread and click on the link I provide and go from there. The controller is located next to the steering column on the firewall by the brake pedal.
All this is assuming you have an unblocked heater core that the hot water is circulating thru. Check that first. Be very very gentle handling the H/C tubes that exit the firewall. They are old and if you break one, you will be looking at a big PITA to replace the H/C. Reverse flush that thing to get it cleared out.


[Modified by 89 Paul in Cal, 2:14 PM 3/13/2004]

jobberone

Great post and I really appreciate yours and all the others. I've just not been able to get back to everyone but I promise I will check back with an update as soon as possible. Thanks again all.

GKK

After checking all the obvious heat related things in my 89 Vette, (heater door, heater lines, fuses...), I decided to check the heater control circuit board located above the gas pedal (little black box). I took it apart and found two solder joints that had separated from the board, I resoldered it, turned the heater on and the heater worked perfectly! :hurray:

frankrizzo1

there was no heat in my 94.......
I flushed out the heater core.....
and was amazed at the amount of junk, gunk and rust that came out of there.....
problem solved....

good luck.....

bogus

any news?

jobberone

Nada. My crew is forcing me to get the boat ready for offshore. Spent the last two weeks cleaning, welding, repairing, yada. Not cold here so taking a backseat. Thanks for everything so far guys and will get back with you.