Hot Air Only Blows?
06-19-2011, 09:18 AM
#1
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Thread Starter
Hot Air Only Blows?
Happy fathers day....got an 82 with a non functioning ac, the thing is it only blows HOT air even with the blower off. Why? Please help with pictures.
06-19-2011, 09:25 AM
#2
Burning Brakes
Join Date: Jun 2011
Location: Saddle River, New Jersey / Corolla, NC
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I had a similar problem on my 964.
The reason was a deteriorated flex duct before the damper. Without the damper connected the hot air just poured into the car.
Again, very different from your 928, but I thought it might lead you in the right direction
The reason was a deteriorated flex duct before the damper. Without the damper connected the hot air just poured into the car.
Again, very different from your 928, but I thought it might lead you in the right direction
06-19-2011, 09:42 AM
#3
Racer
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Try replacing the heater control valve, blocked mine off last week worked great the new one is going in today. First check for vaccum, then operation. Not sure about the 82's but the 86's are behind the MAF.
06-19-2011, 11:05 AM
#4
Instructor
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u can find the heater control valve under the airfilter, these valves are plastic and are closed when the get vacuum with a vacuumline, check the line for vacuum,
99% of the time the valve is bad. its a cheap and weak thing. it gets bend inside and leak hot water to your heater.
airco can be difficult and expencive,
the controlunit where u can choose hot or cold (hvac unit) can be bad, or the vacuum relais
the wiring to the arircopump, the sensors,
best thing is to do a surch at this forum and try to eliminate as much as possible ,
be aware, not all hvac units are the same, there is at least an old style and new.
99% of the time the valve is bad. its a cheap and weak thing. it gets bend inside and leak hot water to your heater.
airco can be difficult and expencive,
the controlunit where u can choose hot or cold (hvac unit) can be bad, or the vacuum relais
the wiring to the arircopump, the sensors,
best thing is to do a surch at this forum and try to eliminate as much as possible ,
be aware, not all hvac units are the same, there is at least an old style and new.
Last edited by riviera455; 06-19-2011 at 02:21 PM.
10-09-2011, 01:37 AM
#6
Nordschleife Master
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10-09-2011, 06:31 PM
#8
Rennlist Member
iF THE HEATER VALVE HOLDS VACUUM, ITS PROBABLY NOT THAT. dont mean the caps.
If it gives cold air when set to min temp (18C?), but goes full hot as soon as you move temp lever, its probably the temp sensors have an open circuit. Check the connector under the left fender, in the hose to the alternator. The sensor itself is probably ok, usual culprit is the 2 pin connector in that lead, as its exposed to water and debris in there. There is another sensor inside, under the little round grille on the dash - bit harder to get at, but also less likely to be the cause. if the under fender connector doesnt fix the problem, do a search for posts under my name, where I got diagnostic help from others as to which wires and where to test under the console, a couple of years ago.
jp 83 Euro S AT 54k
If it gives cold air when set to min temp (18C?), but goes full hot as soon as you move temp lever, its probably the temp sensors have an open circuit. Check the connector under the left fender, in the hose to the alternator. The sensor itself is probably ok, usual culprit is the 2 pin connector in that lead, as its exposed to water and debris in there. There is another sensor inside, under the little round grille on the dash - bit harder to get at, but also less likely to be the cause. if the under fender connector doesnt fix the problem, do a search for posts under my name, where I got diagnostic help from others as to which wires and where to test under the console, a couple of years ago.
jp 83 Euro S AT 54k
10-09-2011, 10:14 PM
#9
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Go to our web site, then tips, then Wally's World, then HVAC. Read the paper to get a better idea of how the system works.
Read the section on finding vacuum leaks. If you have vacuum leaks, the outside/recirculate flap defaults to the outside air position, so air enters with everything off. If the rubber seal across the back of the engine compartment is missing (firewall to hood seal) hot air from the engine compartment flows straight into the HVAC air intake.
If the motor mounts have collapsed (they usually have) then hot air will flow thru the shifter opening in the floor and flow out of the console.
Read the section on finding vacuum leaks. If you have vacuum leaks, the outside/recirculate flap defaults to the outside air position, so air enters with everything off. If the rubber seal across the back of the engine compartment is missing (firewall to hood seal) hot air from the engine compartment flows straight into the HVAC air intake.
If the motor mounts have collapsed (they usually have) then hot air will flow thru the shifter opening in the floor and flow out of the console.
10-09-2011, 10:22 PM
#10
Rennlist Member
Thread Starter
I want and need that A/C system to work perfectly. What hesitates me is pulling apart that dashboard. I am afraid with as old the car is, all sorts of plastic parts will start to break.
Another thing is that the PO said the A/C work but the Evaporator Core needed replacing. I know the compressor works. I wonder how much I may end up spending once I pull apart that dashboard and get inside the guts of that thing.
Its the unknowns that worry me...
Another thing is that the PO said the A/C work but the Evaporator Core needed replacing. I know the compressor works. I wonder how much I may end up spending once I pull apart that dashboard and get inside the guts of that thing.
Its the unknowns that worry me...
