Community Forums

CamJam1 · 10-25-2021, 12:52 PM

The Workhorse Chassis Guide says that the cooling fans should run continuously when the a/c is on or any time that the coolant temperature exceeds 221 degrees. Mine do run when the coolant temp climbs, but not when I turn the a/c on. Any ideas about where to look? I'm thinking there must be a bad pole on a switch or maybe a loose connection.

**Lt Dan** · 10-25-2021, 12:56 PM

I had the same issue with our Workhorse. The service company I used wound up having to wire in a relay connected to the A/C compressor wiring so the fans would run any time the compressor ran.

CamJam1 · 10-25-2021, 02:54 PM

Thanks for the tip, Lt Dan. That might be a good solution if all else fails.

So is there one large fan for cooling the engine and then two smaller fans for the a/c condenser, or just the two smaller fans for both? Sorry, my coach is not here at present or I'd just go out and look for myself.

CamJam1 · 10-25-2021, 07:30 PM

So now I'm not sure what to think. I took the Dolphin in last week to have the air conditioning serviced. They found that it was low on refrigerant and were the ones that told me that the fans weren't working when the a/c was on. This didn't surprise me as the a/c would blow warm when in traffic. They checked for blown fuses, didn't find any, and then called me to see if I wanted to pay them to troubleshoot wiring. Knowing that this could take hours I decided that was a job I'd rather do myself, so I paid them for the work they had done (recharging the system and checking for leaks) and picked up the motorhome.

The a/c worked fine on the way back to the storage yard. Once there, while walking passed the front of the motorhome (with the engine running and the a/c on) I could hear what sounded like the fans running. Sure enough, I looked through the grill and could see that the two small fans were indeed spinning. Scan gauge told me that the coolant temp was 200 degrees, not enough to turn the fans on according the Workhorse Chassis manual.

My question is, could recharging the system have caused the fans to start working again, or should I be looking for an intermittent connection?

donr103 · 10-25-2021, 08:25 PM

Yes.. if you were low on refrigerant.. then fans would not come on.. unless eng about 220 or so.. and if a/c system is full of refrigerant then fans come on as soon as a/c is turned on.. for verification.. go to nearest auto parts store and grab a book for basic automotive air conditioning repair book.. and it will explain in detail why.. great addition to the rv library
Good luck and let us know what you did and maybe better members then me will help you

CamJam1 · 10-25-2021, 08:48 PM

Quote:

Originally Posted by donr103

Yes.. if you were low on refrigerant.. then fans would not come on.. unless eng about 220 or so.. and if a/c system is full of refrigerant then fans come on as soon as a/c is turned on.. for verification.. go to nearest auto parts store and grab a book for basic automotive air conditioning repair book.. and it will explain in detail why.. great addition to the rv library
Good luck and let us know what you did and maybe better members then me will help you

Ok, that's good news then. Thanks for the information. Not sure why it was low on refrigerant if it doesn't have a leak (they tested it with nitrogen) but I suppose it's possible that the mobile tech I used last year to replace the compressor didn't add enough refrigerant.

All that's left to do now is clean the dead bugs off the condenser from the last trip.

Isaac-1 · 10-26-2021, 03:27 AM

My understanding is that those fans are controlled by an air conditioner pressure switch, not a temperature switch, as their primary function is to regulate air conditioner head pressure.

David 70 · 10-26-2021, 06:25 AM

What Isaac1 said. They are controlled by the high pressure switch, otherwise they would run needlessly on the road. So far as not cooling much when in traffic it is pretty much the consensus on this forum that you will not get much cooling when in slow traffic or sitting at a stop light. It sucks but it is what it is.

Fyrflie · 10-26-2021, 08:48 AM

Quote:

Originally Posted by CamJam1

Ok, that's good news then. Thanks for the information. Not sure why it was low on refrigerant if it doesn't have a leak (they tested it with nitrogen) but I suppose it's possible that the mobile tech I used last year to replace the compressor didn't add enough refrigerant.

All that's left to do now is clean the dead bugs off the condenser from the last trip.

On my AC system, I would have to add refrigerant on a yearly basis. Even had a shop check the system. Nothing found.
I started checking the system myself and found the Low Pressure switch was loose so I snugged it up. Also checked and found the low pressure port valve stem was leaking so I snugged that up also.
I added some refrigerant from a can and I am going on three years of no leaks and cold air when I need it.
I found the low pressure switch leak because of an accumulation of oil and dirt around the fitting. The other leak was found with soap and water.
The AC system is a closed system and if there is a lack of refrigerant then there is a leak somewhere.

CamJam1 · 10-26-2021, 10:06 AM

Quote:

Originally Posted by David 70

What Isaac1 said. They are controlled by the high pressure switch, otherwise they would run needlessly on the road. So far as not cooling much when in traffic it is pretty much the consensus on this forum that you will not get much cooling when in slow traffic or sitting at a stop light. It sucks but it is what it is.

Not disagreeing that fans are controlled by the pressure switch, but they are also designed to come on when coolant temp reaches 221 degrees. The pressure switch would sure explain the fans not operating when refrigerant was low though.