Volvo Repair: Air Conditioner, blown head gasket, chevron techron

Question
QUESTION: Robert,

When I run the air conditioner my 2001 Volvo v70 2.4t runs rough and the whole car vibrates. Also, it seems that I am having to fill the coolant on a regular basis. I have taken the car to Volvo on a few occasions with no resolve. At first, they thought it might be corrected with the
replacement of the throttel control but no such luck. Any suggestions?

ANSWER: Any faults stored? If not the fuel injectors could be clogged or not spraying a good pattern. Cooling system needs to be pressure tested, a slow leak at the heater core may be difficult to verify. Check for a possible blown head gasket.

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QUESTION: No, no faults stored which makes it difficult to verify. I haven't had the fuel injectors checked nor have they checked the cooling system pressure (would that be checked during normal maintance checks?). I am afraid to ask: how expensive might it be to fix the fuel injectors or the cooling system. My fear is that the compressor might need to be replaced???

Answer
If the symptom of rough running is present it should be easy to diagnose. Whenever a coolant loss is experienced, a pressure check of the system should be performed, it is inexpensive.The compressor won't cause a rough running problem.Moreso the idle speed may be too low with ac on and it feels rough.A fuel additive like Chevron Techron can help keep your fuel injectors clean.If a head gasket is blown,it is a costly repair.