A/C control unit on the fritz

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Dec 18, 2008 | 06:18 PM

JB90vette

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A/C control unit on the fritz

Hello,
I have a 1990 vette and the (A/C - heater) control unit turns on and off by itself. I hear some clicking sounds in the dash....is this a relay problem or the control unit???

Thanks for your help,

Dec 18, 2008 | 11:11 PM

CorvetteMike2024

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From: So. Cal.

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1990

Not sure about 90 but my 89 has the c68 electronic controls. You have the electronic or manual HVAC controls?

Dec 19, 2008 | 12:46 PM

JB90vette

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Quote:

Originally Posted by CorvetteMike2004

Not sure about 90 but my 89 has the c68 electronic controls. You have the electronic or manual HVAC controls?

It's electronic.......push button's, no levers.

Thanks,
JB90

Dec 19, 2008 | 12:58 PM

runner140*

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From: Ft. Lauderdale Fl

Quote:

Originally Posted by JB90vette

It's electronic.......push button's, no levers.

Thanks,
JB90

Try the easy fix's first. Check out your check valve....universal check valves cost around $5.00. At any auto parts store.

Dec 19, 2008 | 07:45 PM

rodj

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From: Australia

Quote:

Originally Posted by JB90vette

the (A/C - heater) control unit turns on and off by itself.

Are you talking about the head unit inside the car or the heater blower ( fan )?

Dec 20, 2008 | 10:23 AM

JB90vette

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Quote:

Originally Posted by rodj

Are you talking about the head unit inside the car or the heater blower ( fan )?

Not sure what you mean by the head unit, but the fan does turn a low setting with 75 deg. Sometimes I am able to turn the control off, however, it turns back on given a few minutes and gets stuck blowing hot air.

Driving in Florida with the heater on is a pain in the butt

Dec 20, 2008 | 10:25 AM

JB90vette

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Quote:

Originally Posted by runner140*

Try the easy fix's first. Check out your check valve....universal check valves cost around $5.00. At any auto parts store.

Thanks a lot. I'll look into this and see if that helps.

JB90

Dec 20, 2008 | 06:24 PM

rodj

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From: Australia

Some notes.
Even if the valve on the hot water supply is stuck open , hot air is only obtained by the door inside the ducting directing air through the heater core.
A stepper motor moves the door as needed to get the set temp.Something is driving the door to hot.

Florida fix.
Put a manual valve in place of the suggested vac one on the coolant line to heater and turn on when needed.