Low budget SAAB Viggen AC Reinstatement
Posted: Thu Apr 21, 2016 10:43 am
The SAAB's AC failed right around 2011, about when I discovered the oil pressure issue. It turns out that these may have been related, in that the low speed fan resistor can fail and result in both of these issues.
If only the car had a real temperature gauge, this would have been obvious. At any rate, the low speed fan is supposed to be engaged when the AC Is running. With no working low speed fan, condenser temperature, and therefore pressure, can get very high, causing various pieces to leak. Refrigerant escapes, and the system goes from working poorly at idle/traffic (poor condenser cooling) to never working.
My hope is that this is the result of failed O-rings. However, my plan forward is this:
1. attach manifold gauges and check for refrigerant. I expect there will be none.
2. Run car with AC on max, and short the low pressure switch on the system to determine if the compressor clutch works. I will also be able to see whether the compressor is very noisy. If the compressor fails this test, Rockauto sells a GPD compressor for about $100. This will be a tempting replacement for this project. The Four Seasons one is $200. I can't find anything bad about GPD online...
3. Check system for leaks by pulling a vacuum. If it is not leaky, and the compressor is good, then this could be a very cheap job. I would just replace the receiver/dryer and charge the system. Maybe a new expansion valve? They are only $20...
If it is leaky, I will need to determine where it leaks. My guess is at the compressor somewhere, because I saw a neon looking puddle under it once when the engine was out. but that could be anything!
Now, what are my odds that this is just a blown out o-ring?
If only the car had a real temperature gauge, this would have been obvious. At any rate, the low speed fan is supposed to be engaged when the AC Is running. With no working low speed fan, condenser temperature, and therefore pressure, can get very high, causing various pieces to leak. Refrigerant escapes, and the system goes from working poorly at idle/traffic (poor condenser cooling) to never working.
My hope is that this is the result of failed O-rings. However, my plan forward is this:
1. attach manifold gauges and check for refrigerant. I expect there will be none.
2. Run car with AC on max, and short the low pressure switch on the system to determine if the compressor clutch works. I will also be able to see whether the compressor is very noisy. If the compressor fails this test, Rockauto sells a GPD compressor for about $100. This will be a tempting replacement for this project. The Four Seasons one is $200. I can't find anything bad about GPD online...
3. Check system for leaks by pulling a vacuum. If it is not leaky, and the compressor is good, then this could be a very cheap job. I would just replace the receiver/dryer and charge the system. Maybe a new expansion valve? They are only $20...
If it is leaky, I will need to determine where it leaks. My guess is at the compressor somewhere, because I saw a neon looking puddle under it once when the engine was out. but that could be anything!
Now, what are my odds that this is just a blown out o-ring?