heat problem

[D95]

my 95 LT1 with climate control has a heating problem.If I set heat for 78 degrees it blows hot for the first 15 minutes then it gets colder (lukewarm).If I put temp to 84 or more the temp is very hot and stays hot.Does anyone have an idea of what is causing this?Within 6 months all heater hoses were changed including heater control valve,180 degree thermostat and radiator(delco)
thank you

[rascal_rascal_99]

Welcome to CAC!

I can't really answer your problem, although if it makes you feel any better, mine (92 LT1) does basically the same thing. I usually keep mine set to 73F and it will blow hot air out pretty good until it heat's the car up, then blow lightly and go from being hot/warm air to medium/warm like you're talking about. I always thought it was simply that it is trying to keep the car the temp you set it at and if it get's it a bit warmer than that it would let a little fresher air in to bring the temp back down a little...either that, or we've both got the same problem! lol I've had it for a little over two years now and it's done it ever since I've owned it.

[D95]

Thank You for the welcome rascal.
I wonder if this is a common problem with climate control.I hope someone out there can answer us.I would hate to take this to a corvette mechanic ($$$$$)I have owned the car for 9 months.When I checked the heater,it blew nice and warm.I shut it off after 2 minutes.Maybe I should have posted this in the technical section.I have a feeling it is a sensor.
thanks again rascal

[jmccloud]

Sounds like the ambient air temperature sensor is 'seeing' the radiator warm up. This sensor is near the front right lower corner of the radiator. It's 'easiest' to see from the bottom - but not at all easy to see. It could be the interior sensor but more likely the ambient.
I don't know the resistance readings versus temperature but a 'search' using the tab above for ambient sensor resistance should produce a table of values for both sensors.
The sensors aren't that expensive but a dealer will charge an arm and a leg to put one in. Once the bad one is identified, it's a piece of cake to do yourself.
Hope this helps.

[D95]

Thanks for the reply
-Is it common for the ambient temp. sensor to go bad?Ill look into this as soon as it gets a little warmer outside
thanks again

[jmccloud]

Yes, ambient air sensors go bad. They're just a thermistor but the connections are 'tender'.
You had your radiator replaced. Did they get the ambient air temp sensor correctly located?????? If the sensor is touching the radiator, your symptoms would occur.

[Roadster Guy]

D95....
The suggestion that it is a sensor makes sense. But, here's something that puzzles me still about my 96 and may be a cheap fix for you.

Last year I had similar heating issues as you. As a matter of fact in the early spring and late fall I had to set the climate control in the 80's to stay warm......I assumed it was a sensor and planned to look into it next spring. When I took my Vette in for it's pre storage oil change in December, as part of the package, they did a pressure check on the cooling system and actually demonstrated to me my rad cap not holding pressure. So we put on a new rad cap....no big deal. Funny thing, on the half hour ride home I had plenty of heat and the climate control set at about 72......took it out for one last run that night and noticed the same thing on quite a cold night.

Anyway, I don't know enough about it to say if this is just coincidence or what, but I just thought I would mention it as my symptoms were so similar to yours. It could still be I have a bad sensor that is perhaps intermittently faulty.......but, hey for the price of a rad cap I'm happy.....

Strange thing as well, my Vette always ran nice and cool, even down in the city with the AC humming in stop and go traffic at a humid 85-90F.

Maybe some of the other members that are a whole lot smarter than me would know if the system pressure not being right would affect the heating or maybe even the sensors.

Welcome to the CAC by the way.
RG

[D95]

Thanks Roadster.
I did replace the cap about 5 months ago for no reason.I will try to find the old cap and see what happens.It is too cold to look at the car-I wish it was spring time.I will also check out the Ambient temp sensor as mentioned by jmccloud.
How cool is your temp?You may have a 160 stat with the fans reprogramed to come on earlier.

[HD2HVETTE]

Thanks Roadster.
I did replace the cap about 5 months ago for no reason.I will try to find the old cap and see what happens.It is too cold to look at the car-I wish it was spring time.I will also check out the Ambient temp sensor as mentioned by jmccloud.
How cool is your temp?You may have a 160 stat with the fans reprogramed to come on earlier.

My 92 has a 160 stat, runs 175-180 degrees, but heat works fine.