I'm recharging my dad's a/c system since his system stopped working. I threw on the gauges and everything was fine, but i noticed the high side pressure kept rising, and the 2 fans in front of the condenser didnt kick on to help cool them off.

I went inside and with the car not running in the on position i pushed and held both auto buttons and after a few seconds the fans started blowing full blast in the interior and i walked out to see the condenser aux fans blowing. When I turned the car on and turned the a/c system on again the fans wouldn't work.

anybody have any ideas on whats going on here?

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1999 Mercedes E300 188k and still going strong!

I've never figured out the exact conditions that the fans require to come on. I know they're variable speed and they slowly ramp up to speed depending on temperatures and pressures.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

i threw the gauges on my 99 e300 and at lower high side pressures the aux fans were turning on. My dads 98 fans at higher pressures werent turning on...the high side got up to 275 before i shut it down and the fans still havent turned on

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1999 Mercedes E300 188k and still going strong!

Did you monitor the high side pressure from the digital readout? That will tell you if the pressure sensor is bad or not. Hold down the REST button for several seconds and when the display mode changes toggle up and down with the auto buttons. It is item #7 on the display. The fans should surely have been activated long before it got to 275 PSI if the sensor and controller were working properly. First check the sensor, then, if the sensor is OK check item 20 which is the current to the aux fan.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

ok i went and played with the setting in the climate control and now the fans seem to be working???

I have the low side at 30 and the high side fluctuates between 225 and 250...is the high side pressure too high? It seems like something is wrong since the air does get cool, but it doesnt get cold.

i first started the car, ran the diagnostic, and recorded these values

1 - 32
2 - 30
3 - 45
4 - 37
5 - 48
6 - 68
7 - 13
8 - 54
9- - 02
10 - .8
11 - 2.5
12 - 4.3
20 - 2.6
21 - 06
22 - 00
23 - 00
24 - 13.1
40 - 71
41 - 36
42 - 72
43 - 152.

I also went through and get error codes

B1227 - outside temperature indicator temp sensor
B1231 - ECT sensor
B1234 - Sun sensor
B1459 - Series interface (k2) connection to insturment cluster (A1)

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1999 Mercedes E300 188k and still going strong!

My high side rarely gets that high, especially when under way. I would say mine will peak at about 225 PSI and usually runs about half that (per readings from the internal sensor).

How cold does your evap sensor reading (#5) go? It should be down around 32-40F. How much refrigerant did you put in? Was it completely empty when you started? My gut says it is overcharged. It will cutout if the high side exceeds 300 PSI.

Your readings above, #7 is reading 13bar or about 190 PSI. That's pretty much what mine will read at idle.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz