Electrodynamic

First, I have searched and come up with other topics about the A/C fan not coming on or the main fan never coming on and the car overheating. I have none of the aforementioned problems. What I do have, however, is the following:

I have replaced two lines, the pressure switch, the climate control unit, ECU, and the condenser for the A/C. It holds pressure and draws a vacuum like no other. The system is sealed very well and moisture free. All of this is good.

While charging the A/C my dad and I noticed that the head pressure was pretty high (~340 pounds) and noticed that only one fan was on - the smaller fan close to the compressor. The other main fan wasn't on at all. I did a continuity check on the main fan and then ran 12 volts to it to make sure the fan works, and it works just fine.

I turned off the A/C and let the car run so the temperature would climb in hopes that the main fan would kick in. As most of you know this takes a while, but when it did get near resting temperature the small fan kicked in just long enough to cool down the motor and the main fan never kicked on. I have checked all of the fuses for all fans and they are all good (under the hood fuses and under the dash fuses).

My question is, when does the main fan come on? Without the main fan on while the A/C is running there is not a lot of air moving across the condenser which will cause head pressure to be quite high.

I can/will wire up the main fan using a relay off of the compressor +12v wire so the main fan is always on when the A/C is on so there is ample air being pulled across the condenser, but I am wondering when does the main fan come on?

Thanks!

gnxpro24

iTrader: (1)

I actually just had to fix the main fan today. It would not turn on so finally I changed out the fan switch on the thermostat housing. I have 3 ls engines so I tested all the switches to find one that worked first. Then when I installed it I found that the fan only comes on at 205.8 degrees which is weird in my opinion. I ended up having to wire the fan on a new relay and to the fan switch because it refused to turn on connected to the stock wiring. If I were you, before you buy or change anything I would get a simple digital thermometer and take the cap off of the radiator. then put the thermo probe in the water (top off the radiator first with water) then start the car and let it idle til the temp nears 185 degrees. If the fan doesnt kick on by 207 then maybe I would worry.