View Full Version : 88 gts heater issues

12-11-2010, 07:58 AM
I have an 88 gts and my heater will be blowing hot then randomly for no reason switch to cold. It chooses to work most of the time but some days it stops working.

I don't think the heater core is blocked because it comes back randomly and is fine after that.... everything is electronic for the climate controls... maybe a short???

Any input would be awesome, thanks

12-11-2010, 08:55 AM
never noticed that one when i had it, must be new. take the center console out and check to make sure all the connections in the rear are tight, i did take that out. im sure i put them back in tight, if you cant solve this ill take a look at it. it just might need a new panel though.

12-12-2010, 03:27 AM
I never had the problem till it got really cold out. I'll check the connections, it's prolly somethin simple.

12-12-2010, 03:28 AM
always is.

12-12-2010, 03:37 AM
Could also be a water pump starting to fail, or thermostat or the lil' mixer valve.

If it was one of these though you would be having cooling issues and your temp gauge would be playing with you too.

12-12-2010, 03:41 AM
i replaced the thermo before i sold it to you.

this is my gts i sold 4thgenceli......

12-13-2010, 06:49 AM
The temp reads steady, no cooling issues at all. I think it's prolly somethin electronic. maybe a loose connection or the heater control valve... which it think is electronically controlled

12-18-2010, 07:26 PM
This should be easy. On the passenger side, in the footwell nearest the center console you have the valve arm that moves front to back and making the air come out hot or cold. The arm is attached to thin piece of metal that is attached to the servo which is controlled by the temp gauge. My controls quit working and the servo would act up causing no heat in the winter. I disconnected the metal and now I push the arm forward for heat, pull back for cool. Unfortunately if I accelerate too quickly or turn the car a certain way the valve arm moves...it moves very easily. If you are looking at the glove box it would be to the left of the lower left of the glove box.

12-19-2010, 08:12 AM
Oh that sounds like it could be why my heat isn't working. I think I'll check the electrical for the servo and see if i can get it to work right

12-19-2010, 08:47 AM
If you have the Automatic temp controls (The on with the buttons instead of the sliders) they are notorious for solder failure on the circuit boards. I have had the problem 3 times in 2 cars. I always have a spare on the shelf in case it happens again. I've read where people have taken them apart and resolder the boards, but it usually only lasts a short period of time...

12-19-2010, 08:53 AM
yeah he has the electric ones.... it might be that but i know when i took the system out it looked to be just fine and you'll usually see where it needs to re-soldered and i didnt see any.

12-19-2010, 08:56 AM
Usually hard to see. The solder internally from heat expansion and cold contraction, puts micro cracks in it. It causes sporadic, then loss, of controls, just blows cold. Sometimes tapping on the front of it makes it work for a minute or 2 if it's not totally crapped out....
Here's a link to the fix.... http://www.st162.net/forums/viewtopic.php?f=48&t=237

12-25-2010, 03:11 AM
That sounds exactly like what's going on. i'll look into re soldering it or just pull one out of another car. at least now i know the cause. It's only doing it every once and awhile so it's hopefully just one or 2 cracks

12-29-2010, 02:36 AM
My celica had the same problem. Some of the plastic teeth in the gears that open and close the heater control valve broke off. I also just disconnected the metal arm and have to open and close it manually. I finally have the part to replace it but since I am so used to the old way after 8 years, I never think to put it in.

01-04-2011, 09:53 PM
I just realized I have the panel with aouto ac... it might be a little more complicated. I've been waiting for a warmer day when I have time to re-solder it.

01-08-2011, 08:17 PM
I took the panel out and re soldered some of the connections I thought looked bad and now it works allot better... still has it's glitches but it's allot better

01-09-2011, 01:16 AM
sweet, so umm when can i see her again....do you think you wanna make this trip to tacoma on the 20th of feb?