AC Condensor Fan high speed testing

leeshephard · 26 Mar 2017

Hi

Whilst troubleshooting (and fixing) a failing footwell mixer servo I noticed an issue with my condenser fan when using the Scantool test procedure. It will run on low speed but NOT on high speed when running the test sequence. I jumpered R14 between pins 30 and 87 and the fan started. I swapped with oil cooler fan relay and it still did not active during the test sequence.

Any idea how to really test if it is working correctly or not? I have a 10 day france/spain trip booked in a month or so and really want to make sure the AC is tip top!

Thanks

Lee

Alex · 26 Mar 2017

Wrong Lee, sorry.

2 Lee Shephards on the forum could be quite confusing

c:

decgraham · 26 Mar 2017

Hi Lee,

This is unusual, as when the fan resistor fails the fan goes to full speed not slow speed.

Below is the test that I followed when my oil cooler fan would only run at high speed. It turned out that the resistor was shot and once replaced all was fine. These resistors packing up is quite a common problem.

"Quote"
First thing was to determine whether the resistors were working or not & ensure the fans worked. Fuse/relay box cover off & identified relays R04 (oil cooler fan) & R14 (A/C condenser fan).

Caution: Keep in mind the relay terminals are energized 12v at terminal 3(30) even with the ignition off.

-Remove relay R04 (oil cooler blower).
-Jump terminals 3(30c) & 7(87c) for slow speed. Fan should run, even with the ignition off. If the fan runs in slow speed, your ballast resistor should be okay.
-Jump terminals 3(30) & 5(87) for fast speed. Fan should run, even with the ignition off.
You can check the A/C condenser fan similarly, removing relay R14.
"Unquote"

ToreB is the HVAC expert and if he doesn't come along I'd suggest dropping him a PM, or check out his web site:

https://www.bergvillfx.com/fanresistor

Good luck.

ATB

decgraham · 26 Mar 2017

alex yates said:
Hi Lee,

Are you talking about your cooling fans on both sides for your rads? They only run at low speed for the aircon. Running at high speed is when the water temp reaches the high speed trigger level (something like 110 degrees).

Alex, there aint no water in our cars, apart from the windscreen washer bottle :wack:

ATB

Alex · 26 Mar 2017

decgraham said:
alex yates said:

Hi Lee,

Are you talking about your cooling fans on both sides for your rads? They only run at low speed for the aircon. Running at high speed is when the water temp reaches the high speed trigger level (something like 110 degrees).

Click to expand...

Alex, there aint no water in our cars, apart from the windscreen washer bottle :wack:

ATB

Yeah I know, hence me editing my original comment. I thought it was Lee Shephard with the 997

c:

ToreB · 27 Mar 2017

The condenser fan shall start immediately on low speed when turning on the A/C, either by the large or small snowflake button.
Condenser high speed is controlled by the "three-level" pressure switch only, not the CCU.

The Scantool testing sequence is made for use in a 964, the early models were able to control the condenser fan high speed, but it was not used.

Cheers,
Tore

leeshephard · 28 Mar 2017

Thanks for all the replies everyone!

Seems then that the Scantool test sequence on the 993 is unable to activate the high speed mode on the fan as this is done via the 2 way pressure switch just above the hvac air box. No need for me to worry then! As you were gentlemen.

Cheers

Lee

AC Condensor Fan high speed testing

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