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Discussion Starter · #1 ·
My 97 C5 digital dual control climate control unit is completely dead. The lights/screen is completely dead and will not light up. I know these have dimming issues and you can fix that by soldering the circuits and i've done that few years ago and was working fine but after less than a year the dimming of the screen light came back and then finally about 2 weeks ago the hvac control unit went dead completely. The heater, a/c buttons including any function buttons do not respond at all. i have no heat, a/c, rear defrost, etc..

I checked the fuse in the passenger floor fuse box and the fuse looks fine. I researched this forum and another Corvette forum found few posts with same problem as mine but those posters never posted back what their problem was and the fix was. Anyone have/had same problem? What was the problem and what was the fix?

Any input is appreciated.
 

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1966 Coupe 454/538hp 4spd of course; 1984 Z51, built 11/83, Blue w/Black Leather factory override..
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Most folks just send the unit in for rebuild.
If that is not for you, stay tuned. I will check the Service manual for diagnostics. May be awhile. Be patient.

C'ya
 

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Discussion Starter · #3 ·
I know my unit screen is not lighting up, i'm not concerned about that at this time. I'm only trying to figure out why my hvac control unit control buttons are no responding????? such as the heater, ac, rear defrost, etc....????

If i send out the unit have the screen lighting problem repaired, I would still have the problem of the controls not engaging the heater, ac, rear frost, etc... ?????
 

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1966 Coupe 454/538hp 4spd of course; 1984 Z51, built 11/83, Blue w/Black Leather factory override..
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11,730 Posts
I know my unit screen is not lighting up, i'm not concerned about that at this time. I'm only trying to figure out why my hvac control unit control buttons are no responding????? such as the heater, ac, rear defrost, etc....????

If i send out the unit have the screen lighting problem repaired, I would still have the problem of the controls not engaging the heater, ac, rear frost, etc... ?????
There were (pre-COVID) complete rebuild services available (not just for the display light issue) as a good option ($200) vs. new unit ($600). You can also search for a guaranteed used unit. Here's the general diagnostics (not the Service manual step by step) for all/most issues, if you decide to DIY:

C5 HVAC
Note: The climate control module houses all computerized controls for automatic climate control system operation and functions (control buttons response).

No Power:
1. Check the climate control system fuse (front passenger footwell)
2. Check the control module (requires diagnostic or scan tool)
If scan tool initiates a connection the CM is active and working
If no connect, the control module is dead or has a wiring issue
3. Reset the control module
4. After an upgrade or adjustment (battery change, etc.) the control system may not come on until you reset using the scan tool.

No Cooling:
1. Air coming out of the ducts is warm
Check for:
low/exhausted refrigerant
damaged or faulty refrigerant circuit (leaks, compressor, fuse, relay, plugged
orifice valve )
In op Blend Air Door control motor inside the HVAC unit
Compressor lubricating oil topped off
2. Temperature doesn’t correspond with settings:
Check for:
A faulty interior temperature sensor
Damaged Blend Air door control motor.
3. A/C or heater is turned on without effect (no air of the ducts)
Check for:
faulty fan rotor or the blower fan relay
condition of and/or disconnection of vacuum hoses (firewall)
Note: A vacuum leak can damage the main electrical harness.

4. Dimly, Faulty, or No display
Either irregular, temporary, or constant occurs when the solder joints for the power supply resistor become faulty (internal circuit board)
Re-solder
Verify resistor output

5. Air fails to blow out from certain ducts (partial operation)
Check for:
Faulty Air Control door motor (position changes and air distribution to air vents)

Inconsistent cooling
Inconsistencies in operation to reach or maintain an accurate temperature
Check for:
Faulty control module
Uneven air distribution (See #5.)
Compressor squeal (replace compressor)
The climate control panel displays dimly or no display (See#4)
 

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Any explanation my environment control couldn't work? At the point when I fire up the vehicle the Climate Control Unit doesn't fire up. At the point when the snap the buttons on the CCU nothing occurs. Did I blow my radiator? Or on the other hand perhaps the CCU turned sour? How might I check?.


snaptube vidmate
 

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1966 Coupe 454/538hp 4spd of course; 1984 Z51, built 11/83, Blue w/Black Leather factory override..
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What are your DTC's (engine running) if any?
Manual or Automatic contols?

Are you getting power to the HVAC?

Manual w/A/C:
IP Elecrical Center: 10A Mini-Fuse #18, 30A Mini-Fuse #49, to Red wire to Blower Control Module, Brown wire to Blower Motor Relay.

Automatic Dual Zone w/A/C: IP Elecrical Center: 10A Mini-Fuse #16, 10A Mini-Fuse #18, 30A Mini-Fuse #49, Orange wire to HVAC Control Head (hot all times), to Red wire to Blower Motor Module, Brown wire to HVAC Ignition Positive Voltage (hot in ON) .

Do you have good ground at Splice Pack #202 (G202 Black)? See #5 Illustration below.

My advice: Buy R/R working HVAC Control Unit that matches yours.

Font Technical drawing Auto part Automotive exterior Automotive window part


C'ya D
 
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