I have been having an on going problem with my air con, have finally been able to find someone who has been able to re-gas my car using a compatible gas to R12 but it hasn't fixed my problem, air con runs cold on first start up then gets back to natural air temp after 20 minutes or so. My guy feels that I probably have a problem with the expansion valve but cannot locate where it's positioned and how to get at it
Air con issue???
- Thread starter SoulC
- Start date
Go to the NSX Prime Library link in the red banner at the top of the web page. Click on the link and you will find a link to the service manuals. Down load the 1991 service manual and on page 22-71 you will find a diagram showing the location of the expansion valve which looks to be right by the Evap in side the HVAC housing.
I have never had to deal with this. From the diagrams, it looks like the valve might be accessible after you pull the blower motor housing off. It looks like it is on the correct side of the evap. If not, the HVAC housing has to come out in which case the dash has to come out. Poking yourself in the eye with a stick is equal fun. There are three temperature sensors associated with the CCU which can cut back the operation of cool air delivery. Make sure they are all OK first because you don't want to go messing with the expansion valve if you don't have to.
I have never had to deal with this. From the diagrams, it looks like the valve might be accessible after you pull the blower motor housing off. It looks like it is on the correct side of the evap. If not, the HVAC housing has to come out in which case the dash has to come out. Poking yourself in the eye with a stick is equal fun. There are three temperature sensors associated with the CCU which can cut back the operation of cool air delivery. Make sure they are all OK first because you don't want to go messing with the expansion valve if you don't have to.
You need a set of gauges to monitor pressures and thus get valuable diagnosis data
www.vehicleairconservices.com
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R134a Pressure Gauge Readings
How to interpret R134a pressure gauges. Understanding air conditioning gauges.
www.vehicleairconservices.com
Yes, diagnosis is always a good thing. If you initially blow cold air I might look at some other places first such as are the condensers plugged up, are the condenser fan motors running and are you icing up because the evaporator is covered with crap (the NSX does not have a fresh air filter).
Yes, the expansion valve can be replaced without removing the dash. Have not done it, but appears very tight quarters.
IF the expansion valve is blocked, that is likely a symptom and not a cause. Black Death would be top on my list, which necessitates a new compressor and clearing of all lines, which is a big job on this car.
If a "black box" diagnosis via gauges show a blocked expansion valve then I recommend going down every other avenue of cause first. "Feels like" isn't going to cut it.
IF the expansion valve is blocked, that is likely a symptom and not a cause. Black Death would be top on my list, which necessitates a new compressor and clearing of all lines, which is a big job on this car.
If a "black box" diagnosis via gauges show a blocked expansion valve then I recommend going down every other avenue of cause first. "Feels like" isn't going to cut it.
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