Runs hot with A/C on

jc7622 · Jul 15, 2008

My 5740C has started running hot when the A/C is on. With the A/C on it will push right up to the red. If I turn the A/C off is drops down to about 3/4. I have recently changed all the lubricating fluids. I didn't change the coolant, but did check its level. It does this even after blowing/washing out the radiator of dirt and fuzz. Any idea where I chould check next?

Unclebuck257 · Jul 17, 2008

jc7622 said:
My 5740C has started running hot when the A/C is on. With the A/C on it will push right up to the red. If I turn the A/C off is drops down to about 3/4. I have recently changed all the lubricating fluids. I didn't change the coolant, but did check its level. It does this even after blowing/washing out the radiator of dirt and fuzz. Any idea where I chould check next?

Just an idea, but I had that happen to me about two years ago with my 5740C and after doing everything you've done, I started to smell something pretty rank too. Tracking the smell down led me to the fans in the roof of the cab. I pulled the panel off from the top of the roof and found that a mouse had gotten up in there and ws basically stopping the fan (s) with his chewed up body. I removed the corpse, cleaned the entire area of whatever nasty remained and then everything ran fine.

Dallas_Lilly · Jul 17, 2008

Does the temp drop down immediately or gradually when you turn the ac off? The reason I ask is in my truck I thought I had a problem one day but the temp would go down immediately, it ended up being a ground strap broken and allowing current to do weird things to the temp gauge.

jc7622 · Jul 17, 2008

It slowly drops down. By slowly I mean a few minutes. I can switch off the A/C and watch the temp drop from the red to the half way point in about five minutes. It will stay at this temp until I turn the A/C back on, at which point it will slowly climb back up.

I was driving with the doors open yesterday and one of the door caught a post and shattered. Now I need to replace that.

xlr82v2 · Jul 18, 2008

Make sure that the radiator is CLEAN... CAN you see light through it?
Make sure that the fan belt is tight and is not slipping
Possibly the thermostat could be stuck... something to think about
If you're working the tractor hard, consider shifting to a lower gear... and/or increasing the RPM
Check that you aren't low on coolant

Just a few things to check...

Good luck with it

cperky · Jul 18, 2008

Is the A.C cooling? I am asking just to narrow down the problem ( engine cooling system problem or A.C. Problem)

jc7622 · Jul 18, 2008

The A/C cools, but the hotter the engine gets the less cool the A/C is. When I stop and wash out the radiator the A/C gets really cool. Then after about 30 minutes it is hot again.

Willis Fecon Bushhogging · Jul 18, 2008

jc7622 said:
The A/C cools, but the hotter the engine gets the less cool the A/C is. When I stop and wash out the radiator the A/C gets really cool. Then after about 30 minutes it is hot again.

Not sure on your model, but some applications have a temp sensor that makes the fan (for radiator) cut on and off. Do you have a clutch on your fan? Can you turn the fan when the engine is off? If most systems run hot with A/C on, its mostly a cooling problem, something is not telling the cooling devices, to work harder. Possible belts slipping. If all this is OK, Im thinking radiator needs removing and cleaning and flow checking by a radiator shop. It sounds like with the A/C on, its puts a load on the engine and something is wrong with the engine system causing it to run hot, radiator, engine, etc. I sometimes get a little long winded on some issues, so bear with me and hope it helps. Example, with A/C off, and the machine working hard and in the right gear, what is the engine temp????lets say its 195 degrees, with the A/C on it may cause the engine to work harder and hotter. Again, not familiar with your machine, but it sounds like a water flow problem (radiator, water pump, engine block, oil cooler, after cooler, hose colapasing, etc) if engine has a problem, like excessive wear, etc it will run hot under a load.
look at bottom of water pump and see if you see and water or rust. If a pump is bad, it could be sucking air and you will have less cooling.
I have had radiator hose suck together, under a load.
look inside radiator and see if you have good flow (engine running and up to temp) be careful doing this.
When the engine runs hot, there is a sensor for the A/C system that cuts the A/C compressor off, to prevent high head pressure
Good Luck

cperky · Jul 18, 2008

Willis Fecon Bushhogging said:
Not sure on your model, but some applications have a temp sensor that makes the fan (for radiator) cut on and off. Do you have a clutch on your fan? Can you turn the fan when the engine is off? If most systems run hot with A/C on, its mostly a cooling problem, something is not telling the cooling devices, to work harder. Possible belts slipping. If all this is OK, Im thinking radiator needs removing and cleaning and flow checking by a radiator shop. It sounds like with the A/C on, its puts a load on the engine and something is wrong with the engine system causing it to run hot, radiator, engine, etc. I sometimes get a little long winded on some issues, so bear with me and hope it helps. Example, with A/C off, and the machine working hard and in the right gear, what is the engine temp????lets say its 195 degrees, with the A/C on it may cause the engine to work harder and hotter. Again, not familiar with your machine, but it sounds like a water flow problem (radiator, water pump, engine block, oil cooler, after cooler, hose colapasing, etc) if engine has a problem, like excessive wear, etc it will run hot under a load.
look at bottom of water pump and see if you see and water or rust. If a pump is bad, it could be sucking air and you will have less cooling.
I have had radiator hose suck together, under a load.
look inside radiator and see if you have good flow (engine running and up to temp) be careful doing this.
When the engine runs hot, there is a sensor for the A/C system that cuts the A/C compressor off, to prevent high head pressure
Good Luck

What he said. I am not an engine person but I do work on A.C. systems from time to time. Sounds like an airflow or overheat problem at the radiator. Could be caused by low water flow through the radiator or low airflow through the radiator. Does your tractor have a thermostat? (not the A.C. thermostat but one in the water coolant loop)

Good luck
Chris

gemini5362 · Jul 21, 2008

I am not a mechanic but I have had stuck thermostats in the coolant loop. I am reasonably positive that is not his problem. A thermostat that is stuck closed will not cool the engine down when he shuts off his A/C. The thermostat could theoretically be only opening part way but it has been my experience that rarely happens it is either closed or open. If I was going to look at anything in his coolant loop I would consider belts slipping hoses getting worn or collapsed. Water pump problems or possibly in the wierd category a bad radiator cap. If the cap does not hold pressure and allow the coolant system to presurize that has a tendancy to cause things to overheat easier. All the above are after you have followed the excellent advice and made sure that the radiator outside is dirt free. The other thing I might think about is if you have changed from the standard battery to a bigger battery and be blocking air flow into the radiator.