Air Conditioning Troubleshooting Help

STSCowboy · Post by **STSCowboy** » 07 Oct 2019, 20:51

I just bought the 2006 V70 2.5T at Auction so I know no history. The wagon has 131,000 miles on it.

Got the AC working somewhat.

The set up:

Air Source Recirculating On/Off (Subtle Change)
Both Temp Controls Full 62*F
Ambient Air 82*F
Left side Vent Temp 82*F
Right Side Vent 72*F
Both Temp Controls Full Hot (Both get Hot)
Both L/R Vents Get Hot didn’t measure Temps
Blower Fan Midway
Temp Bulb Filthy and Cleaned (No Change)
Auto Temp Control On/Off (No Change)
Blower Speed Variation (Subtle Change on Right Side Only)
The Aft Left Pillar Side Vents only produce Ambient Air Temperature 82F
The Aft Right Pillar Side 74*F

Post by **abscate** » 08 Oct 2019, 05:37

You need a set ofAC gauges to evaluate the low and high pressures to see how much charge is in the system

You can also get a sense by turning it in high cool , then observing the AC lines under hood to see if they sweat , although SD might be a bit dry for that test

STSCowboy · Post by **STSCowboy** » 08 Oct 2019, 18:17

My new to me was having AC issues not cooling so I took it to get it serviced.

They recovered .44 pounds of 134A no leaks at all. It held 29.4 inches of vacuum for 5 minutes after the pulled 29.4 inches of vacuum for 30 minutes.

They serviced the unit with 2.2 pounds of 134A. They then started the car and according to them at idle, I didn’t see the gauges clearly, they said that the low pressure side was reading 30psi and the high side was at 250psi. They told me that 250psi was way too high and that I had a clogged Condenser or Condenser Dryer.

The AC is dropping the Air Temp 40*F from Ambient Temperature which has always been the case for me in working AC units in my vehicles. So I don’t know if they are feeding me a line of bull since I know about just about every part of a car except 134A Air Conditioners.

So if anyone can fill me in on the working pressure specs on the V70 I’d greatly appreciate it.

Thanks,

Joe

Post by **abscate** » 08 Oct 2019, 19:08

40F delta is very good, and they are probably getting fooled by the fact that the P2 compressor is variable displacement.

corrected by jimmy below

STSCowboy · Post by **STSCowboy** » 08 Oct 2019, 21:33

OK thank you

Post by **abscate** » 09 Oct 2019, 05:10

High side 250 psi does seem high, I can check mine next warm day. I don’t think I’ll see 82F until next Maythough

STSCowboy · Post by **STSCowboy** » 09 Oct 2019, 05:51

One thing I need to know is what is the maximum the system is capable of withstanding. I spoke to another respected AC shop and he seemed to think the pressure was ok but I’ll probably stop by his shop to have him throw a set of gauges on it himself.

Post by **jimmy57** » 09 Oct 2019, 08:12

First. If they only checked it idling then don't go back there. EVERY MANUFACTURER HAS YOU ELEVATE ENGINE SPEED for a/c evaluation. 250 psi is not high when vehicle is hot inside and ambient temp is 90 or more and cooling fans are working and the compressor is being turned fast enough to produce high pressures. I think electric throttles may have made some techs lazy to run engine at elevated speeds. You could have 40/250 and raise engine speed to 1200 or more where compressor flow goes WAY up and now it has 10/390 and you have a blockage for sure. Once it cools off in the car the pressures will drop as cooler interior temps also mean cooler gas temps and thus lower pressures.

Only P2 models (north America at least) with variable displacement compressor are the 3.2 6 cylinder and the 4.4 V8. Full VD compressor application started with P3 platform. Cars with variable displacement compressors are somewhat forgiving about needing elevate engine speed since the compressor has higher displacement in part to have enough capacity to cool well at idle and then be controlled to lower displacement when the higher pumping is not needed.

Expansion valve a/c systems (P2, P3, all the new platforms) also help with idle speed cooling as the expansion valve will throttle the refrigerant flow to try to keep pressure drop across high side orifice in the range for higher effectiveness. Orifice tube systems (P80, P1, 700/900) are the worst at idle as that system has no way to offset lower compressor pumping to get better cooling when at idle.

Post by **abscate** » 09 Oct 2019, 08:30

OP - you can pretty much count on jimmy info being 99.999% on point and correct, vs my 1 nine track record.

Post by **jimmy57** » 09 Oct 2019, 10:25

I have worked in the car fixing biz with either wrenches in hand or chalk (later a hand held mouse) for decades. I tried my best to push those I trained to diagnose the right way and told them why. Unfortunately weeks of seeing things done wrong undoes a few days of correctly modeling the right way for so many. Alternators, oil pumps, and a/c compressors fall below rated capacity at idling engine speed