1988 celica gt heating problem? - Toyota Nation Forum : Toyota Car and Truck Forums

tommygunzit · 09-13-2008, 05:32 PM

Hello, i'm new to the forum
I'm trying to troubleshoot a problem on my mothers 88 celica. the heat won't come on on her car. I immediately thought it was stuck thermostat so i replaced it. i've never worked on celica's before and that didn't work. I looked to see if heater core had been bypassed but that wasn't it either. it was all connected. I saw that there were two coolant lines running by the fire wall and also saw a valve. i took the cable off the valve turned manually and tada heat. I figured maybe cable had been knocked ajar when i installed stereo a few months ago inside the dash but when i took dash apart today it was self contained unit. so what the ?
i checked all fuses in engine compartment, drivers kick panel and pass kick panel. All i can figure is that it might be a bad relay? how do i check or is there something else i'm missing? any help appreciated
thanks

tommygunzit · 09-17-2008, 05:54 PM

well i felt around a little more when i heard a clicking noise from under the dash yesterday and it feels like there must be a little motor or something broken that actuates the cable for the heater. is this a replacement part that can be picked up easily or will i have to go to scrap yard. what is it called? is it fairly easy to replace or should i just do dealership
thanks in advance

dgbldr · 09-17-2008, 09:03 PM

I doubt that you have a motor controlling that valve unless it has a fancy auto temp control system.

The control unit in the dash should have an arm of some sort with the cable hooked up to it. The other end of the cable goes to the valve as you already found out.

When you turn the knob from cold to hot, the arm should move the end of the cable. If it does, the other end should move also (at the valve). If one end moves and the other doesn't, you have a broken cable.

fredk · 09-17-2008, 10:37 PM

do you have a slider for the temp?

tommygunzit · 09-17-2008, 11:28 PM

yup its a slider and has auto button on it i believe

Rick89GTS · 09-23-2008, 12:54 AM

Don't bother buying a used heater control unit. More often than not, it'll be bad too after 20 years.
The problem is that the solder joints at the rear of the circuit board crack or develop fractures, breaking continuity and then the control unit defaults to the cold setting. Trust me, I've fixed 5 of these things.
Anyways, remove the unit, exam closely for cracks and resolder.
Lemme know if you need more help.

tommygunzit · 09-23-2008, 01:22 AM

thanks for the tip. i finally got the little motor out yesterday so I'll take it apart and examine to see if it helps. I'll keep ya posted
thanks again

Rick89GTS · 09-24-2008, 12:20 AM

Little motor? Do you mean the heater control panel?

tommygunzit · 09-24-2008, 12:23 AM

there's a motor near the middle of fire wall inside cabin right at the floor. it attaches to a blue cable that goes into engine compartment that turns valve to divert coolant to heater. This is the motor that seems hooped. Are we talking about the same thing?

Rick89GTS · 09-25-2008, 01:19 AM

No. This is the heater control panel I'm referring to. It controls all the servos and motors:

Rick89GTS · 10-05-2008, 01:13 AM

So how'd it go?

tommygunzit · 10-08-2008, 11:47 PM

well i've been busy and haven't had much time but did pull the motor and the control unit which is in the second picture you posted. I will take a look and see where i might resoder. I might just redo everything put back in and reconnect motor to see if it's working. Hopefully it does and I'll keep ya posted
thanks

jayzed · 10-09-2008, 10:15 AM

Can you post some pics? I think I have the exact problem with my 88 Celica GT. Sometimes my heat works great, other times it just blows cold air. Sometimes when I whack the side of the dash, the heat fires up again... I'm not really interested in disassembling my dash. If there is a simple way to rig my heater to only blow hot air, I would prefer to do that, as it is starting to get cold up here and it will be cold until May....

Good Luck,

J

Rick89GTS · 10-09-2008, 05:46 PM

^Disconnect the heater inlet at the firewall and push the cable to the rear. Undo the interior heater flap inside and push that to the rear too. That will give you manual heat until you get the proper fix done.

LInk:
http://www.st162.com/forums/viewtopic.php?t=237

jayzed · 10-09-2008, 07:08 PM

Thanks!

I actually detached that cable and moved the valve towards the fire wall last week and thought that my heating issue was solved, but it still only blows hot air sometimes. I just went out and unclipped that flap. Looks like I should be warm this winter after all!

thanks again,

J