StangMuscle

Hey guys,

So I just installed a bunch of new A/C parts and something weird is going on. I replaced everything but the lines, sensors, and the evaporator core.

So whats happening is my High and Low side pressures are sacked (but not really). With AC on full blast at around 65° I was right within the "standard spectrum" of 25-35 psi (low) and 125-155 psi (high).. This will go on for a couple cycles and then the high side will go all the way up to 325psi before the radiator fans come on and the pressure drops down in the normal range.. What's going on!?!?

I don't know much about AC systems, so I appreciate any help in the matter. My thoughts were maybe a sensor, or possibly moisture?

StangMuscle

Anyone?

StangMuscle

Bump

DRAGUL

I am not sure, but I think the radiator fan is suppose to run all the time with the ac on.

imp

Got it! AC = ON, Electric Fan + ON, or trouble develops. imp

StangMuscle

So your saying, the fan should be on all the time with AC.. Even when the engine isn't hot?

The fan definitely works when the radiator gets hot, but the ac doesn't trigger the fans, except for when the high side reaches 325psi. Any ideas what's causing this? Sounds electrical.. Joy

Derf00

yes, fans should always be on when AC is on, otherwise you don't get an efficient transfer of heat in the condenser core. The condensor core is where the R134A gas turns back into a liquid, the evaporator core is where the liquid turns into a gas. Are you sure you have enough R134 in your system?

Did you vacuum out your system before adding freon? How much freon and oil is the system?

I'm assuming you also replaced the Receiver/drier and orifice tube or expansion valve?

StangMuscle

Yes, I did replace orifice tube and drier. I also did a vacuum before replacing all the parts, but I feel I could have done let the vacuum run longer for sure.. I added 4-5 oz of oil (compressor came with 3 in it), and 31oz of refrigerant.. I ended up evacuating a little as the pressures were a bit high on the gauges.. Still sounds like I need to figure out why fans aren't turning on..

I believe only high is working for my radiator fan, but isn't high supposed to come on with the AC? (Or is it low!?) I'm thinking if I can get the fans working properly I will vacuum and replace all fluids again.. Just to be double sure.

Derf00

Yes, when the AC is on the fan is supposed to come on. I'd focus on that first.

This isn't really relevant for this at the moment but, how long did you vacuum your system for and did you start your car up to warm it up while vacuum? Warming the car up helps to vaporize any moisture in they system and make it easier to evacuate. Also, as a way to leak check before you refilled the system, did you shut the vacuum off and let the system sit to see if it did indeed hold that vacuum for a minimum of 30 minutes?

http://www.4s.com/media/4981741/Four...city-Guide.pdf

Assuming your system didn't have any residual oil in the evaporator you were fine if you added 4 oz of oil. 5 is too much. Freon, 31oz is ok for 05-06 but 26 is for 07-08.

I would focus on your fan first. After that is working correctly, then see what the guages tell you. I don't believe you should evacuate and, vaccum and refill the system again just for the sake of doing it. If you do end up doing that, you do not need to add/remove oil. Just leave that alone.

StangMuscle

Thanks for all the info! I vacuumed for about half an hour, but I never let the pressure sit and check for leaks because I was replacing a bunch of parts (never warmed up the car either, great tip!!).. Probably should have put the vacuum back on afterwards.

Is the only way to remove oil to remove the drain plug? I assumed the vacuum would pull out the oil too.

Do you know any info on the fan/AC combo? Does High or Low fan run with the AC? The fans keep the engine cool (not sure what temp they come on), but they do not come on with AC at all except as mentioned before.