A/C high side pressure spike when condenser fan turns on

[99trollaraSLE]

Hey guys,

I've been having this A/C issue since day one (1 year ago). No one has discussed this problem, so if you're reading this and thinking its been discussed, read it again. The basic symptom is that I blow ambient hot air when i'm sitting idle. This is because my compressor cycles off way too much and doesn't cycle on nearly enough. I'm looking at about 5 seconds on, 45 seconds off. This is due to the below:

My high side pressure spikes upwards of 450 and the low side follows suit a little bit upwards of 45-50 psi whenever the condenser fan motor comes on. This is not intuitive because you expect this to occur when the fan does not turn on. This causes the compressor to cycle off to protect itself. I replaced the fan motor and I get the same problem. Here is the twist: as soon as I disconnect the condenser fan, my A/C works like a champ (low side about 30-40 psi and high side about 280-320). While that pressure is close to normal, it is still high (pressure should be Low side 25-35 | High Side 200-230). So, once I disconnect the condenser fan, the pressure drops down to relatively normal levels and the condenser cycles properly, as opposed to clicking on for 10 seconds and shutting down for 45 seconds in 90 degree heat at a stand still (no this is not normal operation - I mention this because the idiots at midas appear to think its normal).

Here are the typical solutions which can be ruled out:
1. I have proper amount of refrigerant (1.76 lbs)
2. I have no leaks
3. My relays switches are fine (i checked their continuity per FSM)
4. Temperature switches appear to be fine as this is strictly related to fan operation.
5. I have coolant (yes, coolant).
6. Condenser is fine (clearly as its working great with no condenser fan).
7. No obstructions (supra)
8. I haven't checked for A/c gremlins but I did sprinkle r134a pixie dust around the sight glass.
9. Sight glass shows very slight bubbling at idle (750 rpms) which is normal operation per FSM.
10. Alternator is fine (though the fan does appear to draw more power than you'd expect).

So, can anyone clue me in as to why the condenser fan TURNING ON would cause my high pressure to spike like a mofo?

[99trollaraSLE]

bump.... really, no one has any ideas? Bad wiring from condenser motor to relay?


.... what if I told you that in 100 degree weather my car begins to overheat if sitting idle for more than 10-15 minutes. Like when I'm sitting at taco bell stuffing my face with delicious dorito locos taco supremes. I suspect its because the condenser fan also helps cool the engine and at really high ambient temperatures the one fan just isn't enough. But I can't turn on the condenser fan b/c my high side spikes so high I run to risk of literally exploding my AC system. Whats up guys. Someone has to know something.