HeeHaw89

The heat in my elec controlled 89 does not work sometimes. All the functions work properly and the blower works fine, but alot of times it just blows cold air even when cranked up to 90*. Then out of nowhere it just starts to blow hot and function properly. So the car is capable of putting out the heat, just not most of the time. Any one have any experience with this?

Thanks

John Row

This might be of some interest.

forums.corvetteforum.com/zerothread?id=202649

Steve's98

I also had the same problem with my 89 about two years ago. I first replaced the part that John was talking about, but I still had the problem. The heat would come on when I was driving and turn off when I was idle at a light or in park. It turned out that I had a vacuum leak and did not have enough vacuum at idle. I hope that one of the two will work for you.

PTz-92-LT1

Seeing that the problem is intermittant I vote for one of the following 3 things:

1) It is a vacuum leak like suggested above;
2) you are low on water;
3) if it is an electronic climate control the temperature valve actuator motor is shot!

HeeHaw89

Well we can at least narrow it down to #1 or #3 - the coolant level is fine. I've been thinking probably a vacuum leak. But it does have the electronic system. How involved is fixing #3?

PTz-92-LT1

If you have the C68 Electronic Air you should see blinking lights around the time the flow goes from hot to cold. During this time you should also see some error codes. Since the C68 unit does not hold error codes in memory you have to view them while the error is occurring. To get the codes, press the up and down fan arrows at the same time and hold them until the display reads -00. Drive around with this displayed and when the lights start flashing press the Auto Fan button once and notice the codes that are present. My guess is that you will see an 01 and 02. If this is the case there is one more test.

While in the diagnostic mode, press the down arrow until you see a 34, press the Auto fan button and record that number. Press the Auto fan again and then the down arrow until you reach 24, press the auto fan botton once and record that number. These numbers show the call for and the actual deflection of the Temperature Valve Actuator Motor. If they are more than 10 off you have a bad Temperature Valve Actuator Motor. The good news is that they only cost about $45. The bad news is that they take 16 hours to replace in my '92. Not sure what is involved in the 89, although it may be the same.

Before you panic, do the tests and post what you see. There is a remote chance that the problem is interior temperature sensor, exterior sensor, or the sunload sensor. Whatever the case you will get a little closer if you grab the codes form the head unit.

Phil-tha-Rush

I may be W A Y off on this, but the 1st thing that I would check (its free) is my coolant level.

NOT the overflow bottle, but the level in the radiator.

LOW level = no heat

It may be one of the issues mentioned in these other posts, but this is the 1ST thing I would check :D

aroulette

Where can I find the curcuit board?

aroulette

How do you check the coolant level in the rad?

HeeHaw89

Checked it out and it was the Temp Valve Act Motor. Thanks to everyone for your suggestions.