Aircon fault

QI am having problems with a Peugeot 307 with the 1.4 16v EW engine. The owner complained of a non-working aircon. Upon connecting my gauges, I noticed the car was overcharged with R134a. I evacuated a bit of the gas, hoping this would cure the fault, but it didn’t. I then proceeded to replace the expansion valve, but, as before, the blower is working fine and the compressor clutch cuts-in but the condenser fan does not kick-in. I concluded that the ECU was not sending the signal for the fan to kick-in. After looking at the wiring diagram, I tested the fan relay, which was fine. I also changed the pressure switch, to no avail. I get 45psi suction and 75 maximum discharge – here in Malta, one would expect 155psi discharge at this time of year.

In my opinion, there is a problem with the compressor, which would explain the pressures but not the failure of the fan to kick-in, or with the ECU – the compressor is variable output and is not receiving a signal sufficient to produce significant pressure. Am I missing something?

Keith Vella

AHaving already replaced the components listed, the most likely cause is the ECU. However, it should be noted that if the system has been overcharged or overfilled with oil this can damage the compressor.

Normally, a damaged compressor will also be noisy in operation and so hopefully this can be dismissed.

As you have not fully evacuated the gas, it is impossible to know how much is in the system and whether it is contaminated. This may be the problem and it would be best to start from scratch. Depending on the system fitted, the 307 should hold anywhere from 450585 grammes of R134a (details should be supplied by your equipment supplier). Recharging the system will also give you the opportunity to check the SP10 oil.