Poor cab heat

[radman1]

Let us know what result you get. My guess is it won't make any difference. Both thermostats will remain closed because the engine heat won't get high enough to open either one. Although I will admit, that the heater should put out a warmer air at operating temps with a hotter thermostat. I am not impressed with the heat coming out of the heater currently with the lower Temp thermostat.

 

[turbo36]

Let us know what result you get. My guess is it won't make any difference. Both thermostats will remain closed because the engine heat won't get high enough to open either one. Although I will admit, that the heater should put out a warmer air at operating temps with a hotter thermostat. I am not impressed with the heat coming out of the heater currently with the lower Temp thermostat.

I agree but I have to let them try, I will be surprised if it works.

 

[radman1]

Update. Service dept. picked up my JD 3720 and went over it with the regional rep. It performed worse for them getting cab heat than in the past because the temp is now in the low 20's and the engine was not even close to getting warm. They repeated all the things that were tried in the past. Checked for air block, heater control valve, took various heat readings in the cab at the vents, engine temp. etc. At least the regional rep is getting involved. Rep wants to try a hotter thermostat. Both service manager and I think it won't help but will give it a try. Service manager is going to JD meeting in Tampa, FL next week and will try to get some answers. Next plan by service manager is rerouting the hoses if hotter thermostat doesn't work.

 

[turbo36]

Update: The dealer e-mailed me and said the problem is solved and I should have no more issues. They replaced the 160 degree thermostat with a 180 degree as that has worked in the past for poor cab heat issues. According to the dealer with the new thermostat the tractor warmed up in about 10-15 minutes and the heater "would blow you out of the cab". Well, at first I was excited until I realized they tested it in near 50 degree weather so it wasn't a good test. I thanked them and said I would test it on the first cold day.
We got 8 inches of wet heavy snow on Friday so this was my chance to check the "fix" my dealer performed on my tractor.
I started the tractor and drove it out of the barn into the 32 degree weather and waited 20 minutes with the tractor at 1,000 rpm. Unfortunately the results were not the same as the dealer's; the needle on the temp Gage moved about 1/4" from rest but the air temp coming out of the heater ducts was 66 degrees. I ran the tractor up to 2,500 rpm and started blowing snow, after a few minutes the needle moved another 1/8"- 3/16" and the air temp increased to 80 degrees. This is an improvement but certainly not enough if it gets really cold.
Later in the day when the temp moved up to 38-40 degrees the needle moved another 3/16" and the heater air temp increased to around 100 degrees.
It is pretty clear to me that quite simply they have too much capacity to get rid of heat.

 

[Labrat]

I replace my radiator screen with an aluminum panel with 4, 2” holes drilled in it for the winter months. The coolant temp went from 125 at idle to 165 at idle and 185 under load. I think these jd rad fans super cool the block with all the air they move along with the efficiency of these new engines the coolant temps are to low with no engine load.

 

[radman1]

Update: The dealer e-mailed me and said the problem is solved and I should have no more issues. They replaced the 160 degree thermostat with a 180 degree as that has worked in the past for poor cab heat issues. According to the dealer with the new thermostat the tractor warmed up in about 10-15 minutes and the heater "would blow you out of the cab". Well, at first I was excited until I realized they tested it in near 50 degree weather so it wasn't a good test. I thanked them and said I would test it on the first cold day.
We got 8 inches of wet heavy snow on Friday so this was my chance to check the "fix" my dealer performed on my tractor.
I started the tractor and drove it out of the barn into the 32 degree weather and waited 20 minutes with the tractor at 1,000 rpm. Unfortunately the results were not the same as the dealer's; the needle on the temp Gage moved about 1/4" from rest but the air temp coming out of the heater ducts was 66 degrees. I ran the tractor up to 2,500 rpm and started blowing snow, after a few minutes the needle moved another 1/8"- 3/16" and the air temp increased to 80 degrees. This is an improvement but certainly not enough if it gets really cold.
Later in the day when the temp moved up to 38-40 degrees the needle moved another 3/16" and the heater air temp increased to around 100 degrees.
It is pretty clear to me that quite simply they have too much capacity to get rid of heat.

Update. JD service manager is coming to my place to change out the thermostat tomorrow. I know that you changed out your thermostat but still didn't get good results. My service manager and regional rep said the thermostat to use is sort of special for this problem and not the typical, hotter, JD thermostat. He said this one will allows a little bit of flow before it opens, opens more slowly and is a higher temp thermostat. It is suppose to help this problem. They knew of someone in Michigan who had the same problem with poor cab heating. I thought that might be you!(turbo36) He said a dealer in MI changed a thermostat in a 3720 recently but they think he didn't use they correct replacement thermostat. Could that be you?
I'll let you know if the problem is fixed.

 

[turbo36]

Update. JD service manager is coming to my place to change out the thermostat tomorrow. I know that you changed out your thermostat but still didn't get good results. My service manager and regional rep said the thermostat to use is sort of special for this problem and not the typical, hotter, JD thermostat. He said this one will allows a little bit of flow before it opens, opens more slowly and is a higher temp thermostat. It is suppose to help this problem. They knew of someone in Michigan who had the same problem with poor cab heating. I thought that might be you!(turbo36) He said a dealer in MI changed a thermostat in a 3720 recently but they think he didn't use they correct replacement thermostat. Could that be you?
I'll let you know if the problem is fixed.

It probably was my tractor, they just used a standard hotter thermostat, nothing special.

 

[radman1]

Turbo36
Had different thermostat installed today. Temp today was 50, so I don't know if it made much of a difference. My gut feeling is it is the same as before. I did buy a infrared temp gun from HF. The temp at the thermostat housing was 158 after running for 20 minutes. The thermostat is suppose to open at 180 and my guess it is not getting hot enough to open the thermostat. However, under load, the tractor temp gauge now goes slightly higher and the heat blowing out of the heater feels warmer as expected. Next cold day will be the real test.
The new thermostat looked exactly like the old one. The part number for the new thermostat was M811601.

 

[CATMAN]

Thanks for the update radman1. I am still following this thread. You just need a good 20-30F day to test it at idle to 1500 rpm with no load applied to the engine, then see what temperature the cab heater puts out. Did they mention anything about "water hammer" affecting the original thermostat? If this works, I am just trying to find the logic or reasoning if this repair cures your complaint.(seeing how the original t-stat tested OK) I guess we will just wait and see.

 

[wolc123]

What will you do next summer, put the 160 thermostat back in? Would not the higher block temperature, especially with the additional air-conditioning load, shorten engine life?