88 with heat problem

[anapolez]

About a month ago, my heat stopped working. For a few weeks, I rode around with no heat, but the weather was mild...so no problem.

On a trip up to chicago, the heat decides to kick in after about an hour into the trip. I'm thinking...thermostat sticking...but no.. I changed the thermostat and flushed the system and heat still doesn't work when I want it to....but does come on more frequently than in the prior month.

So i go over my uncle's house and we start looking around....we had the heat on and I swear it was turning hot to cold every 5 seconds port so. what's happening is that the valve is opening and closing as it pleases and I actually think the ac compressor is kicking in causing the hot/cold valve to open and close as the compressor turns on and off. I'm thinking that the solenoid must be fried......anyone had any similar experiences or ideas?

thanks for help....if I can fix it I would like to as not to screwed by the labor charges everywhere else.

[Big blue truck]

Is it a electronic heater control. Seen lots that only work sometimes switch from hot to cold. The board inside the heater assembly is FRIED.

[anapolez]

how much should I be looking at for replacement?
do-it-yourself fix or will I have to take it in?

[jimbobillybob]

yes you have to fix it yourself or spend about 600 bucks on a new climate control all that you need to do is remove the center console and glove comp,drivers side under the steering column and four screws holding control in dash.push it in towards the passenger side and pull it out from the hole unplug the harness's and take out the phillips screw holding the printed circuit board.carefully remove the circuit board it has 2 notches still holding it in when you get it out on the backside where the wiring plug is look for where the pins come thru the board and resolder them the solder breaks under the connection where it attaches to the board,the pins next to the screw are the ones that control temp you could just warm those up with a soldering iron or do all of them i did all of mine work's like new,like i said just warming the pin's with the iron will do you don't have to add any solder and don't overheat them,then hook an ohm meter up to those 2 center pin's and slide the controller all the way cold,it will give an infinity reading,in the middle is 1.5 kohms,all the way hot is 0 kohm's,try checking the pin's first wiggling them with the meter probe's the resistance will change,if you don't wanna do that then unhook and wire open the hot water valve,and under the heater box in the middle of the car from the passenger side you have too remove a small plastic shield and unclip the linkage for the door that let's in the hot air from the heater core and move it so hot air will flow in the car.I know it is a little bit of a long story but i hope it help's

[anapolez]

You're the man Mr. Goodwrench!

I would have been all over the junkyards looking for a celica with the needed part.

IF you came up with that fix yourself....again, you are the man.

Thanks again. Hope my issue is the same as yours was.

[anapolez]

Works like a charm.

Everything went exactly as you stated.

Thanks again.

[Beenie]

JimBob, I have to say, you're a genius!! I tried the fix that you described and it worked! A result that I did not get was the meter reading(s) on the pins when positioning the slide control to the cold/medium/hot setting. My reading was (I believe) 1486 kohms in the various positions. Regardless, I have heat. I was starting to get concerned as fall has begun and soon the cool weather will be upon us.

If you read this quote and have anymore insight as to why the meter reading was not the same as what you had gotten, please reply.

Again, your suggestion was brilliant!!!

[Muscle]

jimbobillybob,

I found this same fix at another sight yesterday, without the pin and ohm details. Pulled everything out, the connections looked solid, no cracks. So I put it all back together. Today thought I would search more for possible fix to my intermittent heat problem. I would like to pull everything out again and give it a try but since solder joints looked solid I'm a little leary of pulling everything apart again. Did you see bad solder joints or will only the ohm reading tell the problem?

[Beenie]

Originally Posted by Muscle

jimbobillybob,

I found this same fix at another sight yesterday, without the pin and ohm details. Pulled everything out, the connections looked solid, no cracks. So I put it all back together. Today thought I would search more for possible fix to my intermittent heat problem. I would like to pull everything out again and give it a try but since solder joints looked solid I'm a little leary of pulling everything apart again. Did you see bad solder joints or will only the ohm reading tell the problem?

Muscle,

I did this fix a couple of months ago and though I wasn't able to see whether the pins were suspect, I resoldered all of them anyway. The repair lasted a few (4-5) days. I removed the control and did the repair again and so far the repair has held. One other thing that might be causing the fluctuation of temperature is the slider control. It might have dead spots that have developed over time. Spraying contact cleaner into the opening and moving the slider back and forth should dissolve the crud.

I wasn't able to get the same readings on the ohm meter that JB was able to get, but regardless, the repair did work.

Good luck

[Muscle]

Beenie,

Thank you for the quick response, I'm eager to start tearing apart again but my husband has been leary of the fix. Now with your follow-up I think I can motivate him to resolder the board for me. I can remove everything but I have never done any soldering and he has the experience.

Thanks again for the moral support!

[Muscle]

GREAT NEWS!

It worked for me too! I am now one hot mama, ha! ha!
My husband still didn't think it would change anything but he did warm up the soldered joints for me and I now have heat! I sure hope it last, I took a quick drive to the store, the heat usually drops to cold on my way home, until today! It felt so good I didn't want to turn the heat down even though I was starting to sweat, It's Great!

By the way, while he put the probes on the pins I slowly moved the switch from hot to cold, you could see the ohm readings gradually change from about 5 ohms to 1500 in the middle to full open.

Thanks to all on this Thread!
I don't think I would have ever suspected the control panel could be the problem. I was about ready to pull the heater core and look for a control flap, thinking it was getting stuck open for an unknown reason.