Electric Fans + Air Conditioning = Refrigerant TOO COLD?

[snowblind]

Hello all.

2 years ago I upgraded the cooling fan on my 2001 Suburban from the stock mechanical unit to a dual electric unit. I am using a Flex-a-lite variable temp controller for the power. Controller takes a blue turn on wire from the AC compressor.

Recently my AC compressor failed and I had a new unit installed by a GM dealer. At that time the GM tech told me that the electric fans were "icing up" the refrigerant. His reasoning was that the fans were on the entire time the compressor was running and that caused the "accumulator" to freeze up. It was his opinion that this freezing would cause obstructions in the AC system and the compressor would fail due to running at too high a pressure.

I replied "That sounds very strange to me. Refrigerant isn't supposed to freeze right? Do you think maybe there is some water/dirt/oil INSIDE the system that is causing the freezing" Dealership had no answer.

Fast forward 3 weeks and the new AC compressor starts making failure noises one morning. Compressor has a lifetime warranty but dealership says it's because of the electric fans. I call bull**** and reference some earlier problems with the rear AC that indicate there were particles in the system even though I paid for a flush.

End result, dealership flushes entire system, installs new AC compressor, new accumulator and new rear control valve at no cost to me. Everything is working great but the dealership still says the electric fans will kill the new compressor.

Has anybody heard anything like this? Wouldn't the electric fans be set to cycle on AC mode? Just cut out for 15 sec? What do you do when the fan is on for engine heat?


Thanks,
Matt

 

[CrazyDrei]

Matt,

I recently converted my 2000 K1500 Sub to dual electric fans and flexalite controller. I used a factory fan from a 2007-2011 suburban and have not had any issues. Fans only turn on when AC is on or when the engine reaches a certain temp. Since GM has the exactly same fans and similar GM fan relays I'm with you on this one, the dealer is full of BS and got dirt in the line when they flushed it and tried to pass on their incompetence onto the consumer.

Also what is the outside temperature when you are running your AC? In general it is not recommended to run AC when outside temp is below 60ish degrees Fahrenheit.

Andrei

 

[rayra]

Dealer's retarded. Second half of the GMT800 series comes stock with dual fans. One runs always(?) the other kicks on when you fire up the AC. It's more likely to have to high a system pressure, too much oil, too much refrigerant leading to accumulator or pump trouble, than too much condenser-cooling.

 

[snowblind]

Matt,

I recently converted my 2000 K1500 Sub to dual electric fans and flexalite controller. I used a factory fan from a 2007-2011 suburban and have not had any issues. Fans only turn on when AC is on or when the engine reaches a certain temp. Since GM has the exactly same fans and similar GM fan relays I'm with you on this one, the dealer is full of BS and got dirt in the line when they flushed it and tried to pass on their incompetence onto the consumer.

Also what is the outside temperature when you are running your AC? In general it is not recommended to run AC when outside temp is below 60ish degrees Fahrenheit.

Andrei

In defense of the dealer it is POSSIBLE that the ECU could cut the fan power for 30 sec or so if the AC compressor had been cycling for "XX" number of minutes. This would be possible on both mechanical fans and electric and would most like be the ECU grounding the fan/clutch to turn it on. Those are all things that a custom wired electric fan would bypass because all they have is a blue turn on wire at the compressor.

As to the 60º running. My sub cycles the AC when in defog at ALL temps. Turn defog on and you will here the compressor and fan cycle every couple of minutes. Comes on with recirculate also. No way to disable. And any car with Auto climate is cycling the AC constantly.

It just comes down to the idea that too much fan = bad. Which is hard to fathom for a vehicle that drives down the road at 80mph.


Matt

 

[snowblind]

Dealership FOS as usual.....

My 2006 silverado has a large dual fan setup from the factory, has been that way for 11 years now without "icing up"

Thanks 4BT.

Do the fans ever turn off when the AC is on? I can hear mine cycle off-on for cooling but if AC is on fans are running.


Matt

 

[snowblind]

Looking all over the web I can't find any mention of a fan controller that cycles during AC operation. In fact I actually found products that turn off the fan at highway speeds because the fans are HURTING airflow at this speed. https://www.ronfrancis.com/prodinfo.asp?number=CS-07

The only other item I found in this vein was a switch by Flex-a-lite allowing override to "Full-On" or "Full-Off" Settings. They sell this as proactive "full-power" for towing and a "de-activator for water crossings". https://www.flex-a-lite.com/flex-a-lite-illuminated-3-way-switch.html

I like the concept of the flexalite switch but to help with "Dealership Problem" I would also need a temporary cutoff switch for like 30 secs or so.



Matt

 

[arveetek]

No such thing as too much airflow across the condenser. The point of the condenser is to dump the heat pulled out of the passenger compartment into the ambient air. The more air flow across the fins of a condenser, the better and more efficient the system works. And the refrigerant doesn't ice up internally... it only ices up externally on the evaporator or refrigerant lines if the refrigerant pressure is too low. However, there is already a low-pressure switch in the system that will cycle the compressor off when the pressure is too low. That is why the compressor cycles more on cool days than on hot days, since the pressure is naturally lower on a cooler day.

Casey

 

[Comanche Scott]

No such thing as too much airflow across the condenser...

Casey

x2 :beer:

 

[snowblind]

No such thing as too much airflow across the condenser. The point of the condenser is to dump the heat pulled out of the passenger compartment into the ambient air. The more air flow across the fins of a condenser, the better and more efficient the system works. And the refrigerant doesn't ice up internally... it only ices up externally on the evaporator or refrigerant lines if the refrigerant pressure is too low. However, there is already a low-pressure switch in the system that will cycle the compressor off when the pressure is too low. That is why the compressor cycles more on cool days than on hot days, since the pressure is naturally lower on a cooler day.

Low-pressure switch cycles compressor? Interesting. Guessing it has a high pressure cutoff also which shoots another hole in the dealer's reasons. The cooling fan/condenser efficiency has way too many variables to be used as a critical control unit. Compressors get killed by pressure issues and therefore makes way more sense to protect with a pressure switch.

Refrigerant BOILS at around 15ºF so I agree that there should be no freezing if the system is clean inside. I think my system was very dirty inside leading to the compressor failure.

After 20 min of AC going I see about 1"-2" length of frost on the tube going into the accumulator from the condenser. If I turn off the AC this frost is gone in 10-15 secs. No other frost build up on any hoses.

Thanks for the great feedback.


Matt

 

[rayra]

Frost on the accumulator / line going into it is 'normal', especially in cooler ambient or driveway conditions.

You need to do a proper diagnostic on the operating states of your AC system. Maybe you have a stuck relay and the compressor is running all the time. Need to work thru all the power and switch settings and see if the compressor is operating as it should. Might be a wiring fault. But for starters I'd fire that dealer and find a real AC shop that knows ****** they are doing.

 

[snowblind]

You need to do a proper diagnostic on the operating states of your AC system. Maybe you have a stuck relay and the compressor is running all the time. Need to work thru all the power and switch settings and see if the compressor is operating as it should. Might be a wiring fault. But for starters I'd fire that dealer and find a real AC shop that knows ****** they are doing.

Maybe I don't have any of those things. I would notice the compressor running all the time. I stated before that I believe the entire system was contaminated when the previous compressor failed.

AC is working as it should. Compressor is working as it should. Dealership flushed system and replaced numerous parts at their cost. I'm just making sure that there is no missing detail that other members might be able to advise me on. Information like the pressure switch control for the compressor was exactly the sort of detail I was looking for.



Matt

 

[rayra]

Diagnostic advice still holds for others, even if you already got what you needed.

 

[pugslyyy]

Recently my AC compressor failed and I had a new unit installed by a GM dealer. At that time the GM tech told me that the electric fans were "icing up" the refrigerant. His reasoning was that the fans were on the entire time the compressor was running and that caused the "accumulator" to freeze up. It was his opinion that this freezing would cause obstructions in the AC system and the compressor would fail due to running at too high a pressure.

Dealerships are probably the last choice to take a vehicle that has had any changes made to it to. The techs are under pressure to get the work out, and if they can't figure out (bill) a problem, the easiest thing to point to is any non-standard equipment and move on to the next job hoping it something they can beat the book on.

I own an auto repair shop, have a degree in electrical engineering, and in past lives have run consumer electronics and fabrication businesses (including custom refrigeration systems). So turns out I actually know a thing or two about vehicles, and actually have book learning to back it up. The things I have been told as "fact" that fly in the face of science/physics/etc are amazing, especially by people who aren't aware of my background. Far beyond untangling the extension cord to make the power flow faster stuff.