A/C Fixed - NOT!!! (Long, sorry)

[Kelly in tx]

I have a cab tractor with a/c (Farmall 75C). The a/c went out about a month ago while cutting hay. Hauled it 80/85 miles to nearest dealer. Recently got it back. Bill was $5,768.57. Uffda!!! Mechanic put in almost 23 hours (at $185/hour) and told me how he had to remove both side panels in the cab plus the console behind the steering wheel. Used it for cutting hay again today. After about two hours a/c wasn't blowing very cold. At three hours, no cooling at all. I phoned dealer and talked to shop foreman and mechanic who worked on it. They got me to restart the a/c. Lo and behold, it blew reasonably cold. After another couple hours, not cold. Best (coldest) temperature I measured at vents was 86.6F. I'm guessing somehow it iced up, then ice melted, then blew cold again until iced up again. Ideas?

 

[old]

I have a cab tractor with a/c (Farmall 75C). The a/c went out about a month ago while cutting hay. Hauled it 80/85 miles to nearest dealer. Recently got it back. Bill was $5,768.57. Uffda!!! Mechanic put in almost 23 hours (at $185/hour) and told me how he had to remove both side panels in the cab plus the console behind the steering wheel. Used it for cutting hay again today. After about two hours a/c wasn't blowing very cold. At three hours, no cooling at all. I phoned dealer and talked to shop foreman and mechanic who worked on it. They got me to restart the a/c. Lo and behold, it blew reasonably cold. After another couple hours, not cold. Best (coldest) temperature I measured at vents was 86.6F. I'm guessing somehow it iced up, then ice melted, then blew cold again until iced up again. Ideas?

Freon leak most likely

 

[sleepy1]

Could be to much Freon , neighbors son brought one over once , said it wouldn't cool , instead of clean out the evaporator which was pugged they they just kept putting Freon in it.Cleaned the coils out and recovered 3# of Freon cooled like it should.

 

[Harry in Ky]

Hasn't been mentioned yet, but before taking anything else apart, try pinching of one one of the heater hoses. When ever the A/C blows cold to start with, then gradually gets warmer and warmer, the heater valve is always suspect. Particularly so if it repeats day after day. If it has a shutoff valve somewhere accessible, so much the better. If not two flat washers and a pair of vise grips works too.

 

[NoDakInMN]

If it is icing up, you would notice a reduction in air flow.

But nearly six grand to fix an A/C? Sounds like I should quite my day job in hvac and go into Ag A/C.

 

[bc]

Sounds like another road trip to the stealership. Maybe that one needs a capital S. Stealership.

 

[Fixingfarmer]

Thermostatic deicing probe switch in evaporator not switching compressor off? Also heater lines if they pinched them off I’ve seen someone leave the clamps on made it to the customer. You want the heater to flow just a bit to help with the de icing.

Tubes draining water?

Checking to see your pressure when this happens would help diagnose the problem to see if compressor is A on. you can also check this by hopping out and seeing if compressor clutch is spinning and B if pressure is super high or a little low. You would need a gauge set to test. High side 2.5 times outside air temp for easy figuring.

 

[olddavid]

I have a cab tractor with a/c (Farmall 75C). The a/c went out about a month ago while cutting hay. Hauled it 80/85 miles to nearest dealer. Recently got it back. Bill was $5,768.57. Uffda!!! Mechanic put in almost 23 hours (at $185/hour) and told me how he had to remove both side panels in the cab plus the console behind the steering wheel. Used it for cutting hay again today. After about two hours a/c wasn't blowing very cold. At three hours, no cooling at all. I phoned dealer and talked to shop foreman and mechanic who worked on it. They got me to restart the a/c. Lo and behold, it blew reasonably cold. After another couple hours, not cold. Best (coldest) temperature I measured at vents was 86.6F. I'm guessing somehow it iced up, then ice melted, then blew cold again until iced up again. Ideas?

Yikes!!!!!

 

[caterpillar guy]

Try just running the fan wide open then adjust the temp control til it is reasonably comfortable and see what happens. When I was cutting wheat out on the plains from TX to ID they told the guys to run the fans on high then adjust the temp. This way the air moving through would keep the coil from freezing up and maybe breaking the coil. I doubt being they fixed it in June that it has to much or to little Coolant material in it. That is more winter time fixing problem, and to little would indicate a leak to me since it would have been probably set correctly when fixed. Just my thought on it.

 

[MarkB_MI]

Sure sounds like a low charge. Are you able to pull off a grill or panel and look at the evaporator to see if it's icing up?

The Dometic A/C in my RV ices up after 30-60 minutes of operation. So I switch it to fan-only at least once an hour and wait until water stops draining out of it before switching back to A/C. Next year I'm going to replace it with a different brand, as RV air conditioners are basically non-repairable.

 

[Brendon-KS]

Thermostatic deicing probe switch in evaporator not switching compressor off? Also heater lines if they pinched them off I’ve seen someone leave the clamps on made it to the customer. You want the heater to flow just a bit to help with the de icing. Tubes draining.

Checking to see your pressure when this happens would help diagnose the problem to see if compressor is A on. you can also check this by hopping out and seeing if compressor clutch is spinning and B if pressure is super high or a little low. You would need a gauge set to test. High side 2.5 times outside air temp for easy figuring.

I would disagree that flow through the heater core is desirable when you're trying to cool the cab. Any amount of heater valve leakage, no matter how small, will negatively affect the A/C performance. A lot of machines are equipped from the factory with seasonal shut-off valves in the water line to ensure there is no leakage.

 

[Fixingfarmer]

I would disagree that flow through the heater core is desirable when you're trying to cool the cab. Any amount of heater valve leakage, no matter how small, will negatively affect the A/C performance. A lot of machines are equipped from the factory with seasonal shut-off valves in the water line to ensure there is no leakage.

I don’t argue that for a second that a lot of things are equipped with a manual valve but it’s best if those valves don’t leak to leave them cracked just a hair a turn or 2 on the gate valve. Just like most modern heater valves allow a small amount to bypass.

 

[Tx Jim]

My JD 4255 AC has cooled very good in Texas weather with the manual heater hose cut-off valve I installed over 30 yrs ago closed very tight. I'm curious did dealer service manager get Kelley's pre-approval to perform a $5,768.57 AC repair?

 

[John M]

At least its not a Kubota. I hear they charge you for not doing anything.

 

[John M]

Sure sounds like a low charge. Are you able to pull off a grill or panel and look at the evaporator to see if it's icing up?

The Dometic A/C in my RV ices up after 30-60 minutes of operation. So I switch it to fan-only at least once an hour and wait until water stops draining out of it before switching back to A/C. Next year I'm going to replace it with a different brand, as RV air conditioners are basically non-repairable.

Mark, I dont recall the model of the Dometic on my camper, but it use to do the same thing. The problem, believe or not was with drainage. When it was installed, it wasnt set perfect at the manufacturer, and the water would just build up and not drain fast enough and would cause things to freeze up. (At least thats what I was told) Dealer replaced the top (popup) and it drained fine after that and never froze up again.

 

[MarkB_MI]

Mark, I dont recall the model of the Dometic on my camper, but it use to do the same thing. The problem, believe or not was with drainage. When it was installed, it wasnt set perfect at the manufacturer, and the water would just build up and not drain fast enough and would cause things to freeze up. (At least thats what I was told) Dealer replaced the top (popup) and it drained fine after that and never froze up again.

Mark, I dont recall the model of the Dometic on my camper, but it use to do the same thing. The problem, believe or not was with drainage. When it was installed, it wasnt set perfect at the manufacturer, and the water would just build up and not drain fast enough and would cause things to freeze up. (At least thats what I was told) Dealer replaced the top (popup) and it drained fine after that and never froze up again.

Thanks for the tip, John. I'm pretty sure it drains OK; as soon as I switch to high fan water starts pouring out of it like somebody turned on a tap. I also tried fiddling around with the location of the thermocouple that's supposed to sense the evaporator temperature and that helped but didn't fix the problem.

This is the second Dometic A/C in our camper; the first one quit when it was only two years old. I'd like to find something quieter. Furrion makes a drop-in replacement for Dometic that's supposed to be quieter.

 

[Geo-TH,In]

Sure sounds like a low charge. Are you able to pull off a grill or panel and look at the evaporator to see if it's icing up?

The Dometic A/C in my RV ices up after 30-60 minutes of operation. So I switch it to fan-only at least once an hour and wait until water stops draining out of it before switching back to A/C. Next year I'm going to replace it with a different brand, as RV air conditioners are basically non-repairable.

Mark
If I read the post, the tractor was a 75 C a 2008.
Good chance it was charged with 134a.

Without putting gauges on it, everything is just guessing.
My guess is there is a freon leak and low on gas.

I had gauges for the past 50 years, going back to R12 and R22 and 502.
I had to buy adapters to use old gauges on 134a
Many years ago I bought 30# of 134a at Rural king. I don't think I'll live long enough to use all my 134a.
I can't remember the cost of 30#. I think it may have been about $2 a pound. $60 for 30#.
Not sure what the wholesale cost of 134a is.
I would have to call my nephew if I wanted to buy more 134a.

Finding leaks is near impossible.
ON 2 occasions I put a dehumidifier and window AC in a swimming pool.
The 10 year old dehumidifier had 100's of pinhole leaks in the evaporator.
The AC had a leak in the middle of the condenser.
I junked the humidifier and fixed the condenser leak
If a refrigerator has a freon leak, I junk it.

I would take your RV AC for a swim to look for leaks.
I remove all electrical controls before going for a skinny dip.

 

[Geo-TH,In]

At least its not a Kubota. I hear they charge you for not doing anything.

My next new tractor will be a Tesla.
I hear they have a lifetime warranty on all engine parts, Free ECM scans and free oil changes,

 

[John M]

My next new tractor will be a Tesla.
I hear they have a lifetime warranty on all engine parts, Free ECM scans and free oil changes,

And no nasty diesel fumes.

 

[Geo-TH,In]

And no nasty diesel fumes.

GO GREEN!!
Buy a Tesla tractor.