AC Woes on 2005 XF

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Apr 29, 2025 | 09:45 PM

#21 (permalink)

Romad

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From: Tampa, FL.

Re: AC Woes on 2005 XF

I ordered a used ECU, hopeing it will not have to be coded. Don't know what it would cost to code it, for my vehicle, but If it doesn't work out I can send it back for a refund. Hope it's not VIN coded necessary to work.

Apr 29, 2025 | 10:56 PM

#22 (permalink)

pizzaguy

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From: Fort Worth, Texas

Re: AC Woes on 2005 XF

Quote:

Originally Posted by Romad

The ECU and SKREEM are a matched set and VIN coded. See if you can get them to send the SKREEM as well.

Apr 29, 2025 | 10:59 PM

#23 (permalink)

pizzaguy

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From: Fort Worth, Texas

Re: AC Woes on 2005 XF

Quote:

Originally Posted by Romad

The radiator fan is SIMPLE:

FOUND THIS QUOTE FROM PIZZAGUY, MAR 22/2014
The PTCM communicates it's desire for the fan to run over a single wire, bidirectional, Pulse Width Modulated data stream. When the PTCM wants the fan to run, it "tells" the Fan Control Module to speed it up. There is a two-way pulse sent back and forth, the PTCM 'pings' the FCM and the FCM pings back, indicating all is well.
If the communications break down between the FCM and the PTCM, two things happen:

1) The PTCM alerts you to a possible cooling system failure by turning on a small yellow indicator to the side of the instrument panel, it looks like a little radiator.
2) The FCM goes into "emergency mode" and spins the fan at high speed.

If you do NOT have the little light, it would imply that the ECU is corrupt/bad. But I've never seen this happen - Pizzaguy
If you DO have the light, you have a bad connection between the two modules or a broken wire. or a bad Fan module. - Pizzaguy

The PTCM COULD be bad, but this would be a "first" that I've heard of in over four years on this forum. FCMs go bad kinda often.

PIZZAGUY: WHERE IS THIS LITTLE LIGHT YOU SPEAK OF? I'm guessing it's the radiator light on the dash panel! I just ordered the FCM cause my light does "not" turn on when fans ramp up high. ( Best hunch right now. )

The light is the "Low Coolant" light, that is, the little "radiator light" on the left side of the instrument panel with several other indicators (to the left of the speedo).

See my edits in bold RED.

Apr 29, 2025 | 11:07 PM

#24 (permalink)

pizzaguy

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From: Fort Worth, Texas

Re: AC Woes on 2005 XF

Quote:

Originally Posted by Romad

DO YOU KNOW WHAT FUSE CONTROLS THE CLIMATE CONTROL POWER? The whole Climate Control Panel died at the same time and then the radiator fans ramped up after that. Fuse number 15 checked out good. Haven't checked DUO valve voltage yet.

This is very odd. I know that the Climate control, when you turn the A/C on, tells the ECU to spin the engine fan slowly (if it is not already running due to engine temperature). The very idea that the engine fan is runnning fast at the same time the Climate module is screwy tells me there is more of a "handshake" between the ECU and Climate module than first thought.

Frankly, I'd have changed the climate module first.

From what I see in the manual , the Climate Control fuses are: 15, 33, 37, 35, and 36 (coupe) or 34 (roadster).

In unrelated news, I have accepted a promotion and raise and will be working the next 4 years and 10 months teaching others and supporting products until I retire.
It is time to teach the next generation, I am 65 now and won't be around forever. For this reason, my time here and on Facebook will be limited more than it has in the past.
The hours are long but I'm contributing in a big way - and the money is nice.

Apr 29, 2025 | 11:22 PM

#25 (permalink)

Romad

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From: Tampa, FL.

Re: AC Woes on 2005 XF

Thanks Pizzaguy. I do not have the little radiator light coming on with the engine running. If my ECU is bad what are my options? Can ECU be coded without removing my SKREEM? How will that effect my FOB? I'd rather take a lethal "gang beat down" than trying to get under the dash to remove the SKREEM! All that plastic parts, especially the bezel, want to break just looking at them! Not to mention my bad back and hip!

I just found a ECU cloning service to clone my ECU data into a replacement ECU. Does anyone know about or used this service?

Last edited by Romad; Apr 29, 2025 at 11:37 PM.

Apr 30, 2025 | 09:22 AM

#26 (permalink)

ZERACER

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Joined: Nov 2006

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From: Orange County CA.

Re: AC Woes on 2005 XF

I would talk to MSS, the Mercedese Swap Shop.

Apr 30, 2025 | 10:29 AM

#27 (permalink)

pizzaguy

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From: Fort Worth, Texas

Re: AC Woes on 2005 XF

Quote:

Originally Posted by ZERACER

I would talk to MSS, the Mercedese Swap Shop.

I agree. Keep in mind they do this for a living and have expenses - it would be reasonable for them to charge you for phone consultation.
Those guys know the ECU/SKREEM/other modules intimately.

Apr 30, 2025 | 09:42 PM

#28 (permalink)

Romad

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From: Tampa, FL.

Re: AC Woes on 2005 XF

Quote:

Originally Posted by ZERACER

I would talk to MSS, the Mercedese Swap Shop.

Thanks! They said based on my stated conditions it has to be the ECU. Ordered used ECU and will have it cloned for my vehicle. Thanks again for the suggestion!!

Apr 30, 2025 | 10:04 PM

#29 (permalink)

M60A3Driver

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From: New Jersey

Re: AC Woes on 2005 XF

Quote:

Originally Posted by Romad

Thanks! They said based on my stated conditions it has to be the ECU. Ordered used ECU and will have it cloned for my vehicle. Thanks again for the suggestion!!

I'm glad that you found the answer!