The A/C on my '05 PT Cruiser had not been used for a while, as expected in a
British winter, so as recommended, I ran it for a few minutes. It worked for
a few seconds, then there was a loud honking noise and a blast of steam from
under the hood, as if the radiator had split. I could not find a cooling
system leak, but I did find that the bottom of the A/C compressor was
"sweaty" with oil. The safety valve on the compressor had been blowing off
refrigerant. This looked like a blocked venturi or pressure switch problem.
I took the car to my local garage, expecting a large bill. They gassed up
the A/C system and found that it worked, but the single Radiator Fan
Assembly was not running when the A/C came on. It was an electrical fault
they couldn't trace immediately.
I am an electronics development engineer so I thought I would give the
troubleshooting a go. Power was reaching the fan motor, but it did not turn.
I spun the fan by hand and found that it moved freely, but only for a
fraction of a turn. It was jammed by a pocket telescoping inspection mirror
stuck in the back of the radiator! The handle looked just like part of the
fan support. It must have been lost there almost a year earlier when the car
was in a body shop. With the local cool conditions and only using the A/C on
a run, the car had been OK for a year without a working cooling fan!
Always check the simple cheap bits, however unlikely, for faults before
going deeper.
Brian in London, UK
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