1990 Camry LE Heater Problem

[John Martens]

4 cyl, 350,000 km's, Push button electronic climate control, no A/C.

In the past 2 months I've noticed that the heater will be working fine and putting out lots of hot air the it will suddenly start putting out only cold air. The fan speed does not change. The only thing that will get me hot air back is moving the temperature lever back and forth across the assembly.

The Haynes manual doesn't go into this type of heater control assembly because of the 'complexity'


Thanks from a Camry repair noobie...


John

[Mike Gerber]

Start by checking the level of coolant in the cooling system. It might be low. The heat comes from the hot coolant as it travels through the heater core. When it is low it will give heat sometimes and not other times, as the coolant that is left in the system moves in and out of the heater core. If it is low, fill it back up and you will have heat again, but you have a leak somewhere. Coolant is not consumed by the system. It must leak out somewhre. Have that checked out.

Mike

[fredk]

sounds like the control head might be freaking out, fint the hot-cold control door and see if the motor came loose from it

[es250nut]

Here is some information I've posted before about this type of problem:

Had the same problem in my 87 with the electronic controls.

After much fighting with it, I discovered the sliding rheostat was the problem. It was leaving an open circuit and so the servo that opens and closes the door to the heater core stays closed, leaving whoever was in the car to freeze. I fixed it by re-soldering the contacts on the back of the board.



What you need:
Phillips screwdriver
Continuity tester or Ohm meter
Soldering Iron

First, pull your Climate Control out. Slide the heat control all the way to the Right/Hot setting. Using your Continuity tester check to see if the two pins circled in orange complete a circuit. If you slide the control over, the resistance of the circuit should get higher (bulb on tester will dim more as it moves to the left/cold) until there is an open circuit. If this works as I describe it, the problem is not with the Climate Control. Otherwise remove the circuit board from the plastic case and fold the connector board over so you can resolder the joints I've circled in orange. (You can also test the circuit from these solder joints to see if the slider is still good.)

You can also take a piece of wire, and with the ignition on, jump the corresponding pins in the climate control plug of the cars wiring harness for the heat control. If you can hear the servo motor open the heater door then that part of the circuit is fine. If you can't get your slider control to work, you could put a separate rheostat on that line to operate your heat control separate of the Climate control. If you can't get the servo motor to work that way you will need to check your climate control fuses and servo itself.

Hope this helps, Let me know how it goes.

[ptsmith]

similar thing happens to me (90 176k miles) hasn't happened in a while, actually, not since last season. it usually works on the first try by sliding the control to the middle and then back to hot. don't really have to worry about the heater too much in south georgia though.

[John Martens]

ok..I pulled out the Climate control and tested for continuity on the abovenoted circled pins and solders. That was all working fine.
I followed all the pathways of the entire board and checked for continuity with good results. I managed to find another heater control assembly in a junkyard and installed it and it worked fine
I can hear the servo motors for the RECIRC/FRESH doors and the Air Mix Control switching over the doors quickly when the appropriate buttons are pushed..
Could it be the rheostat that is starting to wear out? I noticed before I took it out that if I wiggled it up and down I would get heat temporarily..
I'd still like to fix this one though...the electronic heater assembly parts are hard to find up here..
I am going to solder those points you mentioned anyway and see if I get any results. Just found the other older link regarding the same problem, sorry for the new thread..

[ironpig]

I'm down in Calgary and there are a ton of camrys in the picknpull here. I can look for you if you like to see if there are parts that you need as i am there quite a bit for my own camry.

[John Martens]

Ironpig,thanks for the offer...might have to take you up on that...There are some 90's camrys in the recycle yards up here but not a whole lot with the electronic heaters....and most of them have been picked over pretty well...Just gotta keep this car running for a few more years....

[ydyjdwp]

i have the same problem with my '88...the info provided by es250nut is right on..my control
panel seems to be fine but shorting the terms on the plug is indicating an intermittent open in the conductors..i manipulated the wiring harness as far as i could reach under the dash and so far no more trouble..will probably have to repair those conductors eventually..just more food for thought

[wilddragon]

I have a question for you guys, last december my heat started flickering in and out, and then it would take me going over a good sized bump to get it to come back on again. However since probably spring it has more or less quit all together. My fluids are topped up so I dont think its that. My camry is a 1990 model however it isnt the electronic push button one as this topic is discussing, its one with the sliding nobs. What I think it is, is that my heater is just possibly hooched, if this is it is it hard to replace and is it expensive? If you dont think it is it what do you think it may be? Also as I just remembered there were a couple times where I could hear the fan struggling to go it sounded rather loud and forced. But I have not heard anything since.

[white90dx]

Originally Posted by wilddragon

I have a question for you guys, last december my heat started flickering in and out, and then it would take me going over a good sized bump to get it to come back on again. However since probably spring it has more or less quit all together. My fluids are topped up so I dont think its that. My camry is a 1990 model however it isnt the electronic push button one as this topic is discussing, its one with the sliding nobs. What I think it is, is that my heater is just possibly hooched, if this is it is it hard to replace and is it expensive? If you dont think it is it what do you think it may be? Also as I just remembered there were a couple times where I could hear the fan struggling to go it sounded rather loud and forced. But I have not heard anything since.

Is it the fan or the heat that stopped working?

If the fan works on some but not all of the speeds, it is the "blower motor resistor" that needs to be replaced.

If the fan doesn't work on any speed setting, you probably need to replace the blower motor itself.

If the fan works, but the heat comes and goes, you need to do what is described in this thread by checking the electronic control panel and the operation of other parts of the system.

-Charlie

[wilddragon]

from what I can tell there is no heat period anymore, whatever heat comes I am assuming is from the engine and is just coming upthrough the vents as it is basically nothing. So I will look into the fan thing thanks

[Mike Gerber]

wilddragon,

You didn't answer white90dx's first question;

"Is it the fan or the heat that stopped working?"

This is an important question to understand what your actual problem is. What happens when you turn the fan on? Does the blower actually blow air in to the passenger compartment?

Mike

[white90dx]

Originally Posted by Mike Gerber

wilddragon,

You didn't answer white90dx's first question;

"Is it the fan or the heat that stopped working?"

This is an important question to understand what your actual problem is. What happens when you turn the fan on? Does the blower actually blow air in to the passenger compartment?

Mike

I just re-read his first post in the thread... he has the slider-type controls. Unless the heater valve cable broke or came unhooked (it happened to me!), he has a problem with the blower motor and it needs to be replaced.

-Charlie

[rmstreic]

Originally Posted by es250nut

Here is some information I've posted before about this type of problem:

Had the same problem in my 87 with the electronic controls.

After much fighting with it, I discovered the sliding rheostat was the problem. It was leaving an open circuit and so the servo that opens and closes the door to the heater core stays closed, leaving whoever was in the car to freeze. I fixed it by re-soldering the contacts on the back of the board.



What you need:
Phillips screwdriver
Continuity tester or Ohm meter
Soldering Iron

First, pull your Climate Control out. Slide the heat control all the way to the Right/Hot setting. Using your Continuity tester check to see if the two pins circled in orange complete a circuit. If you slide the control over, the resistance of the circuit should get higher (bulb on tester will dim more as it moves to the left/cold) until there is an open circuit. If this works as I describe it, the problem is not with the Climate Control. Otherwise remove the circuit board from the plastic case and fold the connector board over so you can resolder the joints I've circled in orange. (You can also test the circuit from these solder joints to see if the slider is still good.)

You can also take a piece of wire, and with the ignition on, jump the corresponding pins in the climate control plug of the cars wiring harness for the heat control. If you can hear the servo motor open the heater door then that part of the circuit is fine. If you can't get your slider control to work, you could put a separate rheostat on that line to operate your heat control separate of the Climate control. If you can't get the servo motor to work that way you will need to check your climate control fuses and servo itself.

Hope this helps, Let me know how it goes.

Don't know if I am posting this correctly, but I am having a problem with my 91 camry's heater, and it sounds like it may be the climate control es250nut has described. I was wondering if es250nut could repost the drawing of the circuit board with the orange circles on it. It is not showing now in this thread.

Thank you!