2000 Golf Mk4
2.0l
automatic
Car had been running quite well. All of a sudden there is a surge in the idle every minute or two and the air conditioning has stopped working. The A/C had been working fine just before this idle problem started.
The A/C compressor does not engage.
Voltage at the fuse box on 5, 16, 25 is all just below battery voltage at 11.xx (hey, it's a 15 yr old harness)
All fuses and fusible links on top of the battery are good. No sign of any melting or corrosion.
Driver's side radiator fan was not working but has since been repaired. (stuck brushes)
Voltage going to the a/c compressor is 4.38 volts but goes up as high as 11.xx when the idle surges. It does not rise with throttle position.
Prior to seeing it fluctuate in time with the surge I had cut open the fan control module and it looks very good inside. I cleaned the contact pads on the 2 relays and with everything re-connected but the FCM left open I can hear a relay close when the a/c button is engaged on the dash. The a/c clutch never engages.
To my knowledge this car has not had a throttle body alignment done in at least 5 years. I have no access to a VAG-COM.
No codes stored according to an OBDII scanner.
I have no pressure gauges to test the high and low side but I've seen no sign of leaks and have no reason to suggest that there is insufficient refrigerant.
With the fan control module completely removed from the car the idle no longer surges. Car idles smoothly.
With the fan control module re-installed each relay can be activated mechanically and the fans come on - the relay closest to the end of the module controls low speed and the other one controls high speed.
The idle surge only takes place with the A/C button pressed in.
2.0l
automatic
Car had been running quite well. All of a sudden there is a surge in the idle every minute or two and the air conditioning has stopped working. The A/C had been working fine just before this idle problem started.
The A/C compressor does not engage.
Voltage at the fuse box on 5, 16, 25 is all just below battery voltage at 11.xx (hey, it's a 15 yr old harness)
All fuses and fusible links on top of the battery are good. No sign of any melting or corrosion.
Driver's side radiator fan was not working but has since been repaired. (stuck brushes)
Voltage going to the a/c compressor is 4.38 volts but goes up as high as 11.xx when the idle surges. It does not rise with throttle position.
Prior to seeing it fluctuate in time with the surge I had cut open the fan control module and it looks very good inside. I cleaned the contact pads on the 2 relays and with everything re-connected but the FCM left open I can hear a relay close when the a/c button is engaged on the dash. The a/c clutch never engages.
To my knowledge this car has not had a throttle body alignment done in at least 5 years. I have no access to a VAG-COM.
No codes stored according to an OBDII scanner.
I have no pressure gauges to test the high and low side but I've seen no sign of leaks and have no reason to suggest that there is insufficient refrigerant.
With the fan control module completely removed from the car the idle no longer surges. Car idles smoothly.
With the fan control module re-installed each relay can be activated mechanically and the fans come on - the relay closest to the end of the module controls low speed and the other one controls high speed.
The idle surge only takes place with the A/C button pressed in.