Continuing A/C odessey
07-12-2005, 01:30 PM
#16
Race Director
Mike
I also forgot that my blue/black check valve was broken & I replaced it? Might as well check yours? From what I remember though your car held vaccuum like it was supposed to?
Brian
I also forgot that my blue/black check valve was broken & I replaced it? Might as well check yours? From what I remember though your car held vaccuum like it was supposed to?
Brian
07-12-2005, 03:33 PM
#17
928 Barrister
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While we are on the subject of AC woes, maybe someone has heard of this
oddity: With the AC button OFF, and the lower slider **** of the controller in the first position from the left (on the white dot), my compressor clutch engages. With the AC button ON, no change occurs, but that should be the only time the clutch should engage. Moving the button back to OFF (not pushed in) doesn't change the compressor clutch from being activated. What say all the wise men/women of this esteemed forum?
I know the controller is toast because the AC stopped working somewhere in the middle of Nevada on my last trip through there, and both rear and front AC blow hot. We suspect the relay in the controller has taken a hike like it does from time to time. But that wouldn't explain why the clutch on the compressor engages without the AC button being pushed.
oddity: With the AC button OFF, and the lower slider **** of the controller in the first position from the left (on the white dot), my compressor clutch engages. With the AC button ON, no change occurs, but that should be the only time the clutch should engage. Moving the button back to OFF (not pushed in) doesn't change the compressor clutch from being activated. What say all the wise men/women of this esteemed forum?
I know the controller is toast because the AC stopped working somewhere in the middle of Nevada on my last trip through there, and both rear and front AC blow hot. We suspect the relay in the controller has taken a hike like it does from time to time. But that wouldn't explain why the clutch on the compressor engages without the AC button being pushed.
07-12-2005, 05:53 PM
#18
Rennlist Member
Originally Posted by Ron_H
While we are on the subject of AC woes, maybe someone has heard of this
oddity: With the AC button OFF, and the lower slider **** of the controller in the first position from the left (on the white dot), my compressor clutch engages. With the AC button ON, no change occurs, but that should be the only time the clutch should engage. Moving the button back to OFF (not pushed in) doesn't change the compressor clutch from being activated. What say all the wise men/women of this esteemed forum?
I know the controller is toast because the AC stopped working somewhere in the middle of Nevada on my last trip through there, and both rear and front AC blow hot. We suspect the relay in the controller has taken a hike like it does from time to time. But that wouldn't explain why the clutch on the compressor engages without the AC button being pushed.
oddity: With the AC button OFF, and the lower slider **** of the controller in the first position from the left (on the white dot), my compressor clutch engages. With the AC button ON, no change occurs, but that should be the only time the clutch should engage. Moving the button back to OFF (not pushed in) doesn't change the compressor clutch from being activated. What say all the wise men/women of this esteemed forum?
I know the controller is toast because the AC stopped working somewhere in the middle of Nevada on my last trip through there, and both rear and front AC blow hot. We suspect the relay in the controller has taken a hike like it does from time to time. But that wouldn't explain why the clutch on the compressor engages without the AC button being pushed.
07-12-2005, 05:58 PM
#19
Under the Lift
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Yep, that is the first thing we did last Sunday. His check valve fell apart in my hand. Fortunately I had a spare. Then the 4-way connector split. We did some surgery and temporarily fixed that. I checked vacuum on all lines and the check valve and they held fine. We did not check the climate control vacuum manifold inside the car, but that is on the agenda. Previously we observed the new heater valve closing properly, but since he has some heat in the core still, we need to review that among other things.
Originally Posted by Greg86andahalf
"even with vaccuum (which you have) the heater valve will leak down and open when the car is off..."
The Black-Blue check-valve (located ner the brake booster) is supposed to prevent this.
BTW, if not done already, make sure the check-valve is not faulty. A common problem is a faulty valve that restricts vacuum, which may prevent the actuators from operating fully, including the heater valve. A defect would be: if you have a vacuum of 16 going in and only 10 or so going to the HVAC. There should be full vacuum through the valve with no drop. When the car is shut off, the valve should prevent vacuum leak-down since it's a one-way device.
Greg
The Black-Blue check-valve (located ner the brake booster) is supposed to prevent this.
BTW, if not done already, make sure the check-valve is not faulty. A common problem is a faulty valve that restricts vacuum, which may prevent the actuators from operating fully, including the heater valve. A defect would be: if you have a vacuum of 16 going in and only 10 or so going to the HVAC. There should be full vacuum through the valve with no drop. When the car is shut off, the valve should prevent vacuum leak-down since it's a one-way device.
Greg
07-13-2005, 01:40 AM
#22
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I have a tremendous respect for the knowledge and experience here. 
Today almost did me in- it hit over 100 and the A/C was NOT up to it, and having windows open even at high speed provided little relief.
Some alternatives:
Can take to Quality Imports to evacuate system, replace drier/receiver and expansion valve at approx $500 cost
Can arrange trip to Stockton given your success, Brian
Other thoughts ? I would not mind if the solution compromises the heater which I have never used in any car in the Bay area or S. Cal.
Thanks for all help and guidance.
Mike
Today almost did me in- it hit over 100 and the A/C was NOT up to it, and having windows open even at high speed provided little relief.
Some alternatives:
Can take to Quality Imports to evacuate system, replace drier/receiver and expansion valve at approx $500 cost
Can arrange trip to Stockton given your success, Brian
Other thoughts ? I would not mind if the solution compromises the heater which I have never used in any car in the Bay area or S. Cal.
Thanks for all help and guidance.
Mike
07-13-2005, 04:16 AM
#23
Rennlist Member
Do the expansion valve yourself and save at least a couple hundred. Have them change the oil and flush the system, then change the dryer, evac the system, and put the correct charge in. Also have them sniff around for leaks. If it's not working right, it's possible that not enough oil is getting carried through the system, with obvious consequences for your compressor. Are any of the hoses or fittings anywhere on the system oil-soaked? That would indicate leakage and insufficient oil.
07-13-2005, 10:53 AM
#24
Rennlist Member
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Mike,
If you will send me an email at techAT928gt.com (change AT to @) - not a private message thru this Forum, but an email - I will send you a detailed paper on the 928 HVAC system that might help you.
If you will send me an email at techAT928gt.com (change AT to @) - not a private message thru this Forum, but an email - I will send you a detailed paper on the 928 HVAC system that might help you.
07-13-2005, 12:19 PM
#25
Three Wheelin'
Mike,
My S4 had a bad heater valve. I replaced it with an OEM part and the brand new one leaked. I confirmed this by taking the valve completely off the car and installing two expansion plugs that I had for my personal water craft that fit the hoses perfectly. My mediocre cooling instantly changed to awesome a/c. Before I found this problem I had the system evacuated, replaced the expansion valve and the drier. Have to do the drier any time the system is opened but i'm sure now that the expansion valve was fine. I'd try this first before you evacuate the system and do the drier, valve. Easy to check and would cost less than $5 bucks for the plugs at Lowe's. I keep the plugs in all summer and switch back to the valve in late October.
If you do wind up having to get the system evacuated, find a shop that will pull a hard vacum over night. The longer the better in my experience. I have even threatened to buy a used pump so I could do it myself for at least 24 hours. The less moisture in the system the more efficient it will be and the longer it will last.
Heres hoping it is something easy/cheap.
Regards,
My S4 had a bad heater valve. I replaced it with an OEM part and the brand new one leaked. I confirmed this by taking the valve completely off the car and installing two expansion plugs that I had for my personal water craft that fit the hoses perfectly. My mediocre cooling instantly changed to awesome a/c. Before I found this problem I had the system evacuated, replaced the expansion valve and the drier. Have to do the drier any time the system is opened but i'm sure now that the expansion valve was fine. I'd try this first before you evacuate the system and do the drier, valve. Easy to check and would cost less than $5 bucks for the plugs at Lowe's. I keep the plugs in all summer and switch back to the valve in late October.
If you do wind up having to get the system evacuated, find a shop that will pull a hard vacum over night. The longer the better in my experience. I have even threatened to buy a used pump so I could do it myself for at least 24 hours. The less moisture in the system the more efficient it will be and the longer it will last.
Heres hoping it is something easy/cheap.
Regards,
07-13-2005, 12:24 PM
#26
Race Director
Mike
The quick easy fix (that should help) is the zip tie heater valve....on my car it was good for about 20 degrees colder air....I used to get around 20-30 under ambient, now I get around 50+ under ambient....low 40's on a 100 degree day is typical....once yours is working properly it will perform the same!
I would order a drier ($23.69 from specialists, the expansion valve is only $29.45..."O" ring sets are only $17.00). So the parts aren't that expensive...its the labor and R12 that gets pricey! But its worth it to stay cool!
Geff's right about the hard vaccuum...my shop tested my car overnight to make sure all was good!
When are you going to work on it next?
Brian
The quick easy fix (that should help) is the zip tie heater valve....on my car it was good for about 20 degrees colder air....I used to get around 20-30 under ambient, now I get around 50+ under ambient....low 40's on a 100 degree day is typical....once yours is working properly it will perform the same!
I would order a drier ($23.69 from specialists, the expansion valve is only $29.45..."O" ring sets are only $17.00). So the parts aren't that expensive...its the labor and R12 that gets pricey! But its worth it to stay cool!
Geff's right about the hard vaccuum...my shop tested my car overnight to make sure all was good!
When are you going to work on it next?
Brian
07-13-2005, 01:42 PM
#27
Three Wheelin'
My heater valve leaked even with the zip tie trick. I think they don't seal all that well under the best of conditions. I have read on the list of several owners having new or nearly new ones leak. That is what prompted me to take it completely out to test the effect.
