A/C Heat Problem
Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
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From: San Clemente CA
A/C Heat Problem
Heat and air has worked off and on since I got this car.
Now, it only blows hot air. The a/c compressor is cold.
I assume there is a mixing box somewhere and the mixing door is staying on hot.
Any common problems that would be a good place to start?
1991, automatic A/C
dell
Now, it only blows hot air. The a/c compressor is cold.
I assume there is a mixing box somewhere and the mixing door is staying on hot.
Any common problems that would be a good place to start?
1991, automatic A/C
dell
Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
Likes: 1
From: San Clemente CA
The problem started as intermittent. A/C was cold for an entire drive some time. Then it started to cycle cold and hot. Still goes cold every now and then but mostly hot. Not outside air, hot air.
Drove the car this morning and the fan started cycling off and on?? but always hot.
Drove the car this morning and the fan started cycling off and on?? but always hot.
Last edited by wdsj; Oct 5, 2012 at 09:56 AM.
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Joined: Aug 2012
Posts: 80
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From: Knoxville TN
Probably the actuator. Double check, but I believe the 90-95 Vette used the same one.
Some have had trouble with certain actuators fitting properly; I'd recommend doing some searching on the forum to see for yourself.
Here's one discussion: http://forums.corvetteforum.com/c4-g...tor-motor.html
Some have had trouble with certain actuators fitting properly; I'd recommend doing some searching on the forum to see for yourself.
Here's one discussion: http://forums.corvetteforum.com/c4-g...tor-motor.html
Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
Likes: 1
From: San Clemente CA
New twist
I just check for codes on the control assembly. No codes and all parameters looked acceptable (table on 1c1-5).
With the car idling and A/C in Auto, the blower cycles on/off about every 5-6 seconds (blower on for about 1 sec, off for about 5 seconds then on for 1, etc)
Ideas appreciated.
I just check for codes on the control assembly. No codes and all parameters looked acceptable (table on 1c1-5).
With the car idling and A/C in Auto, the blower cycles on/off about every 5-6 seconds (blower on for about 1 sec, off for about 5 seconds then on for 1, etc)
Ideas appreciated.
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Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
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From: San Clemente CA
Blower fan is cycling.
another data point:
I disconnected the power plug to blower motor and monitored voltage to the motor. Voltage comes on the does not cycle, it stays at 12v+.
Plug the motor in, it comes on and in less than 20 seconds it goes off and cycles on/off. Unplug when motor is off and measure voltage at <1. In 10-20 seconds, voltage on AND IT STAYS ON ??
Plug it back in and the motor cycles.
When the motor is running it is smooth and quite. Could it just be a bad blower motor? Any feed back mechanism that would make the controller cycle the motor when plugged in, but not when not pluged in?
added: when I ran the above test, the engine was running.
another data point:
I disconnected the power plug to blower motor and monitored voltage to the motor. Voltage comes on the does not cycle, it stays at 12v+.
Plug the motor in, it comes on and in less than 20 seconds it goes off and cycles on/off. Unplug when motor is off and measure voltage at <1. In 10-20 seconds, voltage on AND IT STAYS ON ??
Plug it back in and the motor cycles.
When the motor is running it is smooth and quite. Could it just be a bad blower motor? Any feed back mechanism that would make the controller cycle the motor when plugged in, but not when not pluged in?
added: when I ran the above test, the engine was running.
Last edited by wdsj; Oct 5, 2012 at 01:05 PM. Reason: added information
Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
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From: San Clemente CA
Need someone smarter than I.
With the key in start but motor (engine) not running. The blower runs, no cycling. Run fan speed from 1 to 10 to 1 and blower smoothly changes from slow to fast to slow. No cycling.
Crank the car and the blower cycles on and off. wtf?
With the key in start but motor (engine) not running. The blower runs, no cycling. Run fan speed from 1 to 10 to 1 and blower smoothly changes from slow to fast to slow. No cycling.
Crank the car and the blower cycles on and off. wtf?
Last edited by wdsj; Oct 5, 2012 at 01:05 PM.
Thread Starter
Instructor
Joined: Sep 2012
Posts: 141
Likes: 1
From: San Clemente CA
After reviewing all the wiring diagrams, I concluded I must have a wiring gremlin.
Checked resistance through connectors and found a high resistance in the connector to the blower control module. Reworked that connector and cleaned all others I could get to and, everything seems to be working just fine. A/C is ice cold and it switches from cold to hot and back.
cool
On to my next problem, they is always another one.
Checked resistance through connectors and found a high resistance in the connector to the blower control module. Reworked that connector and cleaned all others I could get to and, everything seems to be working just fine. A/C is ice cold and it switches from cold to hot and back.
cool
On to my next problem, they is always another one.