RK37 AC

[TractorGuy]

If it's a problem with the heater control it will blow cold at first and then get warmer as the engine warms up.

 

[cdb2]

So a bit more on this.
I confirmed the compressor is turning off and on with the dash switch as it should
The compressor is not cycling often which would indicate a low freon situation
Temp of the blowing air seems to be unchanged by turning AC on or off or moving the dial from hot/cold

At this point I'm leaning toward an issue with the hot/cold dial.

I dont have means to take it to the dealer and I doubt they would cover under warranty anyway.

You may want to download a copy of the TYM service manual for their equivalent model, it should have cut away drawings and troubleshooting info for the AC system that may make diagnosis easier. They should definitely cooler it under warranty, and if you can get the problem narrowed down you may be able to get them to send you parts by mail.

 

[chesternator]

I found the issue but im not sure how to fix it. The hot/cold dial has a flexible rod that runs in and out of a sleeve to move the damper? Problem is the rod and sleeve just flex and wont push the damper. It will pull of course which is heat. I used a long tool to manually push the lever and I have AC again. Once I move it to heat it wont go back to AC using the knob

 

[pacerron]

Did you ever find a fix for this? My RK55 which is a little over 2 years old developed the same hot air only problem a couple days ago.
I have 460 hours on it and it ran very cold during the summers for the past 2 years. The other day, a 90 degree day, it got super hot in the cab with the ac on and fans on high.
Opening the top hatch, the side windows, and the back window still felt like a steam bath.
The heater is supposed to be electric so it is not a hot water valve problem.
My compressor does run with the clutch engaged continuously and doesn't start and stop as you said yours did. I doubt if the AC system is covered on a unit over 2 years old?
The RK store really doesn't have a shop. Taking it in this time of year for days or to have them ship it back to the assembly plant in Ohio defeats the purpose of owning the tractor.
I have 2 other tractors but they are open with just a canopy but cooler than the RK55 with cab presently.
I'm going to try a can of coolant with a guage on it but have my doubts for a fix if it was a sudden leak. I notice the rubber low pressure hose from the compressor takes some pretty tight turns back at the firewall and may have rubbed a leak.
Could you give more detail and or pictures of how you got into the hot/cold dial rod to move the dampener?
Does the hot/cold control panel pull/pry out from the ceiling hole it sits in to get to the rod?
Thanks in advance..

 

[LouNY]

I would be surprised if you found that your tractor actually had electric heat for the cab.
Often cooling issues are plugged condensers or evaporators as well as plugged up cab air filters.
Or dampener controls it seems like on RK's.

 

[pacerron]

I would be surprised if you found that your tractor actually had electric heat for the cab.
Often cooling issues are plugged condensers or evaporators as well as plugged up cab air filters.
Or dampener controls it seems like on RK's.

Electric heat surprised me a little too looking through the manual.
I haven't really had time to get into it yet. Had to mow a large horse pasture this morning. Luckily the outside air was much cooler today but the cab still got hot after an hour or so with all the windows and roof open.
I am very suspicious of the dampener but haven't figured out how to get to it yet? Hopefully Chesternator or others will offer help/solution soon.
All my filters are clean and the compressor clutch is engaged when I turn it on briefly to check.

 

[LouNY]

Interesting; that would be nice on a cold morning it should provide almost instant heat as soon as you can
raise the engine rpm.
So it must have a second alternator just for the heat elements.
Does it also have hoses bring engine jacket heat back to the cab? I didn't see any mention of hoses or heat exchanger.
I've never seen that in a tractor before, my 2015 RAM eco-diesel had some supplemental heaters in the heating system.

 

[grsthegreat]

Why would someone use electric heat when the tractor provides hot water. Very weird. Guess there prepping for all electric tractor conversion.

 

[pacerron]

Thinking about the electric heat after discovering it in the manual.
The mention of somebody in this thread or another that they somehow pulled/turned the dampener cable with pliers or something because the knob didn't work, really threw me off in trying to figure out the problem.
After finding in the manual that the heater is electric makes me think the Hot-Cold Knob really controls a rheostat switch. When it is on cold the heaters are off. As you turn it more toward red the heater coil gets warmer and warmer. The AC compressor is controlled by the separate Off-On knob. The fan speed is controlled by the third knob.
Pretty simple if that is the way they did it.
No water lines or little ceiling radiator to leak, take up space, or lose a lot of heat in the long path from the engine/radiator to the cab ceiling. No dampener doors or cables to get stuck, leak or broken. The front of the cab ceiling is lower than the rest of the ceiling to make room for the AC/heat unit, the control box, and a radio on the left side.
I checked the hot/cold knob on my control box last evening and it feels like it is engaged with the shaft as it makes a lot of very close clicks if it is turned slowly.

My wife picked up a can of 134A refrigerant with a gauge on it yesterday in town. I'll try that soon to see what the current pressure is on the low side and add refrigerant if it is low.
If not low, then back to square one.

 

[pacerron]

Since Chesternate has not updated his fix yet, I would like to report that I fixed my RK55 this afternoon which had the same problem of blowing air hotter than the air outside the cab with the AC on full and fans at highest speed. I had the same condition of the compressor clutch being engaged constantly.
When I put the gauge on the low side it read Low but just a bit below the Normal range. So I added as much freon as the system would take from the 18 0z. can per directions. That brought the gauge up about half way on the green ok section of the gauge. Approximately 40 psi. There was still a little more freon in the can but the pressure of it must have been equal to the pressure in the low pressure line so it would not discharge into the line. The temperature became very cold in the cab as soon as the freon was added. So I used the tractor for a couple hours with the AC on high to distribute the small amount of oil and the leak sealer the freon can contained. After 2 hours I was almost frozen so put the tractor in the barn for the night.
It will be interesting to see if the freon pressure in the system holds or if it leaks out soon.
I must admit that I have not run the AC much in the wintertime so any slow leakage was probably personal error on my part.

Hope this helps somebody else.