Need Help with '86 HVAC
Thread Starter
Burning Brakes
Joined: Jan 2001
Posts: 1,218
Likes: 2
From: Plainfield IL
Need Help with '86 HVAC
The heater on my '86 does not work at all. The A/C works intermittently. The A/C compressor clicks on and off when the control is set. Sometimes it engages constantly. Other times it engages for a second or two and then disengages. The silver canister adjcent to the A/C compressor is cold.
It seems odd that the heater and A/C have a problem at the same time. Could the problem be the dash A/C and heater fan control switch?
Before I start throwing parts at the problem, I wanted to ask for suggestions.
It seems odd that the heater and A/C have a problem at the same time. Could the problem be the dash A/C and heater fan control switch?
Before I start throwing parts at the problem, I wanted to ask for suggestions.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Sounds like the A/C compressor and system is basically working.
Does the blower blow air OK?
Do the vents change as you select the different ones?
Are the hoses hot to the heater core?
If all yes, then I would look at the blend door assembly to see if it is working.
Does the blower blow air OK?
Do the vents change as you select the different ones?
Are the hoses hot to the heater core?
If all yes, then I would look at the blend door assembly to see if it is working.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Usually the A/C compressor cycling on and off is caused by low refrigerant charge.
Do you have the C60 standard A/C or C68 automatic HVAC system?
If the C68, you can query the system to find out if any codes are stored. There was a thread (or two) on this somewhere...
http://forums.corvetteforum.com/c4-t...stic-mode.html
If you have a C68, you probably have a problem with the blend door motor resistors on the HVAC programmer (located on the firewall above the gas pedal). Here is info on that:
http://www.batee.com/corvette/acrepa...oard/index.htm
He is wrong about the resistor values. They should be 140 ohms.
Do you have the C60 standard A/C or C68 automatic HVAC system?
If the C68, you can query the system to find out if any codes are stored. There was a thread (or two) on this somewhere...
http://forums.corvetteforum.com/c4-t...stic-mode.html
If you have a C68, you probably have a problem with the blend door motor resistors on the HVAC programmer (located on the firewall above the gas pedal). Here is info on that:
http://www.batee.com/corvette/acrepa...oard/index.htm
He is wrong about the resistor values. They should be 140 ohms.
Thread Starter
Burning Brakes
Joined: Jan 2001
Posts: 1,218
Likes: 2
From: Plainfield IL
Thanks for the input. My car does not have the C68 Electronic Climate Control.
The blower blows air sometimes when set to A/C. It does not blow air at all when set to heat. Also, vents do not change when I select the different ones.
I'll have to check to see if hoses to the heater core are hot. I'll check the blend door assembly, too.
Could the problem be the blower relay (p/n DR1034)?
The blower blows air sometimes when set to A/C. It does not blow air at all when set to heat. Also, vents do not change when I select the different ones.
I'll have to check to see if hoses to the heater core are hot. I'll check the blend door assembly, too.
Could the problem be the blower relay (p/n DR1034)?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
"The blower blows air sometimes" -- is the blower motor running when "does not blow air at all"?
"vents do not change" sounds like you don't have any vacuum at the A/C controller. It's what controls the various doors in the HVAC system. Does your cruise control work? They share the same vacuum port on the plenum (and the vacuum check valve).
The blend door is controlled by a metal cable from "HOT - COLD" lever on the A/C controller. You should be able to remove the resistor assembly and see the blend door movement through the hole.
The blower relay bypasses the blower speed resistors and applies 12 volts directly to the blower so it runs at full speed. I have seen a blower resistor break. I don't remember if that caused all the lower speeds to not work or just the one associated with the broken resistor.
"vents do not change" sounds like you don't have any vacuum at the A/C controller. It's what controls the various doors in the HVAC system. Does your cruise control work? They share the same vacuum port on the plenum (and the vacuum check valve).
The blend door is controlled by a metal cable from "HOT - COLD" lever on the A/C controller. You should be able to remove the resistor assembly and see the blend door movement through the hole.
The blower relay bypasses the blower speed resistors and applies 12 volts directly to the blower so it runs at full speed. I have seen a blower resistor break. I don't remember if that caused all the lower speeds to not work or just the one associated with the broken resistor.
