2006 Volvo S40 A/C cools for 20 mins. and then blows hot

2006 VOLVO S40
35,000 MILES • 4 CYL • 2WD • AUTOMATIC
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HERBERT JONES
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I have had the a/c system charged and had dye to check for leaks - no leaks found. After the a/c stops cooling, and is turned off for 10 mins. it will cool again when turned back on.
I had it checked again today by another mechanic. He got it to stop cooling and checked the electrical to the compressor. He followed it back to a relay and replaced the relay with another but there was no power. He jumped the relay terminals and could make the compressor kick on. There was no power to the relay. He then followed the wiring further back and ran into some other relays and electronics.
Once the a/c stops cooling and the a/c is turned off for a short time and then turned back on, it will cool until it blows hot again.
He does not know where to go from here.....I hope you can help.
Aug 26, 2010 at 9:56 PM
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JIS001
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Did they check for voltage at the compressor clutch connector? Or did they assume there was no power since the clutch stopped working? The most common problem is that the compressor clutch clearance is out of spec since it is worn out. The clearance should be between 0.3mm to 0.5mm If it is greater then that what happens is as the weather gets hot, the clutch begins to expand causing the clearance to get wider. So as the clutch engages and disangages during its cycles, the clearance gets too wide that the magnet can not pull the clutch back in. So make sure he actaully verifies there is power when the compressor quits either by using a volt meter to check for battery voltage or a simple test light.
Aug 27, 2010 at 1:26 AM