A/C question
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From: Portland, Oregon
A/C question
I am having a problem with '88 S4 A/C. The front unit does not blow very cold air. By that, I mean it was 85 yesterday and the front unit was blowing 60 degrees while the rear unit was at 42 degrees. We replaced the heater valve with a new, all metal, unit. The previous valve looked like it was working ok from the outside, but inside an o ring had come loose and it no longer sealed. According to my mechanic there is still a problem with the flaps not being able to close all the way. These flaps are in the box that is between the heater core and the a/c evaporator (I think) He told me that the only way to repair that problem is to remove that unit with the flaps, which requires not only removal of the console, but the entire pod and dash as well. He said probably 15 hrs labor just for that part.
I wondered if any of you have a way to get at this box without removing the entire dash assy? I have read through nichols site and Tony H. info on AC and climate control and I don't see this particular problem addressed. Granted, that could be because someone called it something else and I am not saavy enough to recognize it.
I also have the 928 HVAC system white paper from Wally P. where he talks about the setting motor and flaps. I assume this is the same unit. Wally goes on to say that this unit rarely fails, but does sometimes need adjustment. According to the mechanic, he has only seen one other failure of this type that required removal of the unit to repair. In that case some of the felt that was used as seals had come loose and wadded up in such a way that the doors would no longer operate properly. The mechanic said he had to remove it to fix the problem and he would have to do the same with mine.
All suggestions much appreciated.
Thanks in advance
I wondered if any of you have a way to get at this box without removing the entire dash assy? I have read through nichols site and Tony H. info on AC and climate control and I don't see this particular problem addressed. Granted, that could be because someone called it something else and I am not saavy enough to recognize it.
I also have the 928 HVAC system white paper from Wally P. where he talks about the setting motor and flaps. I assume this is the same unit. Wally goes on to say that this unit rarely fails, but does sometimes need adjustment. According to the mechanic, he has only seen one other failure of this type that required removal of the unit to repair. In that case some of the felt that was used as seals had come loose and wadded up in such a way that the doors would no longer operate properly. The mechanic said he had to remove it to fix the problem and he would have to do the same with mine.
All suggestions much appreciated.
Thanks in advance
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You pretty much have all the information you need to get the A/C in perfect working order. Yes, most of the flaps can be adjusted without removal of the evaporator/heater core box. One thing you might want to check first is the operation of the recirculation flap above the fuse box/beneath the glove box. This is what feeds the front unit its air supply. If the vacuum motor for this flap is bad, you will never recirculate internal cool air, with all incoming air coming from outside.......bad for A/C performance.
Even if you have a good heater valve, if there are other vacuum leaks in the system, it will really foul up other flap functions.
Even if you have a good heater valve, if there are other vacuum leaks in the system, it will really foul up other flap functions.
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I don't think you need to open up the console to get at the problem.
1. Make sure your heater valve is working. If it's working, and closed, it doesn't matter if your flaps are open/closed or intermediate. There will be no hot coolant flowing thru the heater core so it makes no difference what the flap location is.
2. Make sure the reciculation flap is working. This is located right above the passenger foot. If the A/C is on and the flap is working, it will be open, recirculating cool air from the cabin. This will help.
3. Ask your mechanic if he's ever worked on a 928 before.
1. Make sure your heater valve is working. If it's working, and closed, it doesn't matter if your flaps are open/closed or intermediate. There will be no hot coolant flowing thru the heater core so it makes no difference what the flap location is.
2. Make sure the reciculation flap is working. This is located right above the passenger foot. If the A/C is on and the flap is working, it will be open, recirculating cool air from the cabin. This will help.
3. Ask your mechanic if he's ever worked on a 928 before.
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From: Portland, Oregon
borland and Aaron
Yes he works on lots of 928's and is very experienced.
Aaron,
I replaced the heater valve. It is working properly. A/C is still not as cold as it should be.
I will double check on the recirculation flap to ensure it is working properly.
Thanks for the responses guys. I appreciate the feedback. keep it coming
Yes he works on lots of 928's and is very experienced.
Aaron,
I replaced the heater valve. It is working properly. A/C is still not as cold as it should be.
I will double check on the recirculation flap to ensure it is working properly.
Thanks for the responses guys. I appreciate the feedback. keep it coming
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Joe;
I'm no expert here, but it occurs to me that a simple check might be to assess the ac operate immediately after a cold startup (like in the morning). If both AC units blow roughly the same temperature, then your problem is somehow connected to the heater valve and/or recirc flap. If the front AC is warmer than the back at startup, then I would suspect the front AC coil or expansion valve.
Another check it to manually turn off the heater valve to ensure it is closed. Would not be the first time that a new part was defective out of the box or on first use.
Might be worth running through Wally's HVAC check to ensure all the diverters and flaps are working as expected. The recirc flap is easy to check...immediately above the central electric panel...you can hear/see it open and close when the AC is turned on.
Regards,
SteveCo in St. John's
I'm no expert here, but it occurs to me that a simple check might be to assess the ac operate immediately after a cold startup (like in the morning). If both AC units blow roughly the same temperature, then your problem is somehow connected to the heater valve and/or recirc flap. If the front AC is warmer than the back at startup, then I would suspect the front AC coil or expansion valve.
Another check it to manually turn off the heater valve to ensure it is closed. Would not be the first time that a new part was defective out of the box or on first use.
Might be worth running through Wally's HVAC check to ensure all the diverters and flaps are working as expected. The recirc flap is easy to check...immediately above the central electric panel...you can hear/see it open and close when the AC is turned on.
Regards,
SteveCo in St. John's
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In a nutshell the rear doesnt have any heater core to deal with, thats why it is colder. If the rear blows colder, odds are you are gettting warm water into the heater core and it is being mixed with the AC air from the evaporator.
If i were you id plug the hose to the heater or cap the fitting that leads to it temporarily as a test then measure your air temp again.
if it is still warm from thr center it could be a a partially plugged expansion valve.
The back blowing cold tells you your compressor should be OK and all the relays.switchology etc etc.
Eliminate all source of heat from the heater core first.
HTH
If i were you id plug the hose to the heater or cap the fitting that leads to it temporarily as a test then measure your air temp again.
if it is still warm from thr center it could be a a partially plugged expansion valve.
The back blowing cold tells you your compressor should be OK and all the relays.switchology etc etc.
Eliminate all source of heat from the heater core first.
HTH
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From: Portland, Oregon
Originally posted by bd0nalds0n
Where did you get the all-metal valve?
Where did you get the all-metal valve?
Napa...
http://www.napaonline.com/cgi-bin/nc...8&prmenbr=5806
you might have to cut and paste that link a bit to get it into your browser, but that's what I am using.
Tony, I will try that idea.
Thanks you guys.
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Tony's right.
First place to look is heater valve. Make sure the valve is closing off the flow. Actually my car had the heater hose permanently plugged with a cork when I got it (Florida car). Couldn't figure out why I couldn't get heat??
Next is the flap. If you are getting outside air because the flap isn't working right, the front will be warmer (assuming the outside air is hotter than inside). This is actually really easy to check, you can do this first but it won't have as much impact as a properly operating heater valve.
Sorry about the crack on your mechanic. I actually wish there were more knowledgeable and willing guys to work on the 928.
First place to look is heater valve. Make sure the valve is closing off the flow. Actually my car had the heater hose permanently plugged with a cork when I got it (Florida car). Couldn't figure out why I couldn't get heat??
Next is the flap. If you are getting outside air because the flap isn't working right, the front will be warmer (assuming the outside air is hotter than inside). This is actually really easy to check, you can do this first but it won't have as much impact as a properly operating heater valve.
Sorry about the crack on your mechanic. I actually wish there were more knowledgeable and willing guys to work on the 928.
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The P.O. owner on my had an all metal it must of failed. They unpluged the heater hose intake, cut the return hose and plugged it where the heater hose intake was. What a hack job.
After reading Aaron's response, it makes sense, since mines a Florida car.
Man it's like 93 degrees today!
After reading Aaron's response, it makes sense, since mines a Florida car.
Man it's like 93 degrees today!
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Just to make sure I understand, you guys are telling me that it doesn't matter if the doors will close all the way as long as no hot water is getting into the heater core, the air should be equally cold from both front and rear?
Yes?
Yes?
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Well...almost yes. If the front A/C is pulling air from outside the car...and it is warmer outside than in...then there will be a difference front to rear. If the outsode and inside temp is the same, no hot water in the heater core should produce the same temps on both A/Cs.
Regards,
SteveCo in St. John's
Regards,
SteveCo in St. John's
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Joe F,
1. Yes. The heater core doors have no influence on A/C temp if the heater valve is closed.
2. The flap in the passenger footwell must be operating to get the same temp front and back. This one is fairly easy to replace if it's not working properly, I did it myself. You have to do some standing on your head but what else is new when working on your 928.
1. Yes. The heater core doors have no influence on A/C temp if the heater valve is closed.
2. The flap in the passenger footwell must be operating to get the same temp front and back. This one is fairly easy to replace if it's not working properly, I did it myself. You have to do some standing on your head but what else is new when working on your 928.