Fan switch not working although fan blows when switch bypassed, but no cold air comes out even though the compressor is working
This is in a 2000 Durango

 

Does anyone have any clues as to why my elec fan would run non-stop? Last summer the compressor locked. I replaced the compressor, condenser, both expansion valves, and both evaporator cores. Vacumed down the system to dry it and check for leaks. Then charged the system with fresh refrigerant by weight. The system now cools pretty darn well but I have noticed that the electric fan runs non stop when the AC is on. The fan should cycle. Also the High side pressure runs low and I'm going to assume that is due to the fan running as if I obstruct the condenser the high side pressure will rise.

I have a feeling there is a pressure sensor in line somewhere that is telling the fan that the pressure is too high causing it to never cycle off. I can't imagine that having the high side pressure lower than normal would be of great concern but I know it's not operating as it should and would like to get it right. Any help will be greatly appreciated.

This is on an 01 Durango R/T 5.9 with front and rear air.

Thanks, in advance, Tony

 

I'm pretty sure the radiator fan should not cycle, it's supposed to stay on as long as the a/c is running. What are your high and low side pressures?

Chart from the factory service manual.

 

Last it was checked was at the end of last year. 86 outside temp, low side 32 high side 110. Just want to make sure all is correct before the weather get's hot here this year (Pittsburgh). I could certainly be wrong but I believe in the past that the Electric fan would cycle, seems that it would run far more when sitting at a light or in town at lower speeds. Then again I could certainly be mistaken.

 

Low side seems fine, but the high side does seem low. Perhaps not enough refrigerant was put in. And it might be that the fan only comes on when the a/c compressor is engaged, so if the compressor was cycling before, the fan might have been too. The only time my compressor ever cycled was when my system was leaking (would up being compressor shaft seal) and was low on refrigerant.

By the way where in Pittsburgh are you from? I grew up between West Newton and Yukon (southwest of Greensburg).

 

Not reallly in Pittsburgh, use that as a reference as most no one would know where Ford City is (45 miles north of Da Burg up 28) Know exactly where West Newton and Yukon are. Many moons ago when I was in PITT I date a young lady from West Newton.

As to the compressor, it does cycle but the Electric fan runs non stop. I by no means am an A/C expert (Programer according to degree, but for close to 20 years now have been a network engineer). I still like wrenching my own when and where ever possible. The charge on the A/C was put in by weight 2 lbs and oil was measured to 8 oz.

Have been through the factory service manual several times and the only mention of any sensor on the high or low side for that matter would be to kick the compressor on as the low side drops or to shut it down when the high side exceeds 450 psi.

Maybe I'm just getting old and the memory is going and the electric condensor fan always ran continuous. I don't know why I keep thinking that prior to the catastrophic failure and replacement of the entire system that was how it worked. It's probably just one of those vivid memories that just never really happened, I don't know.

 

I know ford city is up by butler, never been there though. And I'm also a programmer (degree in computer engineering), so no a/c expert either, just read a ton and learned a lot about it while trying to get my a/c working well last year.

As for the a/c, 32oz seems about right as does 8oz for the oil. I think my 99 calls for 30oz with the rear system, but they changed the rear hvac for 01-03. Now when I replaced my compressor (long story, but I messed up the old one changing the seal) it said all over it and in the manual that oil needed to be added, but luckily I checked first because it has right around 8oz of oil in it already. So if there is too much oil it could be causing the cooling performance to be bad.

And I forget what pressure it's set for, but there is a low pressure shut off for the low side as well. I want to say around 15psi, but don't quote me on it. There is also a temperature sensor in the expansion valve that shuts off if it gets too cold (37° maybe).

My 99 doesn't have the auxiliary fan, so I can't tell you much about how that works.

 

im not sure if the 2000 had the new style two zone system or the old style, but the 01-03 trucks required 2.44 lbs of refigerant for the dual zone system as per the attached sticker off my radiator mount

 

98 dodge ram will not pull in freon holding 25 on vac

 

is the compressor engaging?