My car does not get hot , but the ac does start to fail if I sit in traffic on 100+ days as well, I was told the fans just cannot get the volume of air through the radiator to keep the ac cooling ,, it works amazingly well if I'm moving and my fan is running strong ... Just so much air can come through that small opening with the standard fan ?

 

Spike
In this case, the system is just not doing enough air at idle. My own guess is that this is because the engine, even if you have the biggest alt known to man attached to it pushing the biggest fans, and the most wonderful a/c compressor, is just not turning fast enough to power them.
Why not do a test where on a hot day you set the idle to 1000 rpm (everything going, a/c, fans lights etc) and see what happens in a simulated hot traffic stop? Higher idle does a number of things: pushes the coolant round the engine faster, produces enough amps to power the fans, also, very importantly, makes the A/c compressor produce more cool.
One of those digital voltmeters plugged into the cigar socket will tellyou how high the idle needs to be to get the system up to speed.
Although my car is a V12, the fast idle solenoid I fitted transformed the hot traffic performance of the systems we are discussing.
Greg

 

Greg, that's a good advice, the alt certainly cannot deliver enough amps and the battery will be under strain and voltage decrease when all the systems are sucking current at idle.
Two questions, though:
- that would require to put the gearbox in neutral whenever heavy heat conditions are met in traffic?
- with a good battery well charged, that should not happen unless the car drives for a long time in these conditions?

 

Yes, if stationary for any length of time
No, with a/c compressor load on the engine, three electric fans, interior fans, and possibly lights, radio etc, the volts in the system will drop off very fast indeed with no adequate charging going on. If you stick a digital voltmeter into your cigar lighter socket (about a tenner off amazon) you wil be amazed how fast the voltage drops without adequate charging going on. But the fact the at the compressor is turning too slowly at tickover to do much compressing is a very large contributory factor too.

Greg