I have a 1999 E55 in which the compressor is not engaging. Tried hooking up one of those 134A cans with a gauge on the top and it says it is full and almost redlining on the low side so it seems to have Freon. I pull the values and codes and reset the codes and it still doesn't come on. Here are those values:
1.103
2.84
3.85
4.84
5.87
6.84
8.82
Looks to me like all seems fine while sitting there.
Error codes were
1231
1234
1422
Cleared and still no compressor engagment. Any Ideas on where to turn next?

Thanks Jerry

How, may I ask, did the gauge tell you it was properly charged? I've been working professionally on auto AC for almost 40 years and I can't imagine a gauge telling me anything about how full a system is without running. Even then it takes a lot of experience to get close. The only way to know is to pull it out and measure what goes in PROPERLY, with a scale.

Clear the codes and maybe it will work.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

sweet -
where's your #7 readout?

did you try replacing the evap temp sensor above the gas pedal?

__________________
-- raymond~
47º 34'N 122º 18'W

Based on the stated values the evap temp sensor is not the problem.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

The reading for the evaporator sensor looks right, so that's probably not the issue. Reading #7 may be, but we don't know that one.

After clearing the codes, ensure that nothing came back right away.

As Steve says, it is difficult to tell how much refrigerant is in the system even with the best of gauges and with the compressor running. You don't have the best of gauges and the compressor isn't running.

That gauge is there to keep you from getting your suction pressure too high while you top it off. That's a quick way to kill your compressor.

If the compressor isn't running and there is no suction, you will always see a high pressure there if there is any liquid in the system. The pressure that you see under this condition is entirely dependent upon the ambient temperature and nothing else.

You are so right Matt. If one were to put a gauge on a 30lb cylinder of refrigerant the pressure in it would not matter whether it had 20lbs of refrigerant left or five pounds. As long as there is liquid the presure is governed by the relationship PV=nRT. Basically this states that at a given volume and temp the equilibrium will set the pressure the same always. Thus the pressure on a static system is the same no matter how much refrigerant is in it as long as there is liquid present.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks guys. I guess I will take it to an AC shop to diagnose. I just had the 134A bottle with the gauge on top and hooked it to the low side. It showed the pressure at full and when I tried putting more in it it just inched into the red which read high so I figured I better quit. The compressor never kicked on. Maybe it wont be too expensive of a fix.