Volvo 99 s70 heat stuck on



a/c is charged and cold but when the

engin warms-up the a/c is gone the question is ECC , temp sensor, valve

or damper has to be checked

Can you tell if the A/C is actually turning off, that is the clutch is disengaging or is it just the air that is no longer cold, or is the air actually heated?  Does you car have a second radiator fan that comes on with the A/C?  Is that fan still on when it gets hot?  Does all this happen in a matter of a few seconds or over a few minutes?


the ac clucth is cycling on and off and sweating at fire wall


Is the condenser coil clean? A dirty condenser coil could cause the high pressure control to open.
If the system is marginally low on refrigerant, the low pressure control might not open but the compressor could be running hot and opening the thermal overload protector, but only after operating for a while.

Can you tell if the air coming out is actually (significantly) hotter than the air going in? If so, there is a control problem that is causing the heater to turn on, which would overload the A/C system.


thanks to all replyees,
if the controller inputs are temp sensors
how many and where are they ?