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Discussion Starter · #1 ·
The compressor has perfect pressure for high and low sides. There are no leaks, the pressure remains the same. The unit will heat but not cool. The conclusion is that the flow of the heat pump is not set correctly. In other words, there is a leak from the heat side that keeps the unit from cooling correctly.

The flows for the heat and cool side are adjustable after the cover is removed. There is ZERO information from Deere of how to set these adjustments. As you adjust these, because the cover is off, there is no air flow through the evaporator so it's impossible to tell when the adjustment is right.

There must be some way to set these used at the factory (but not ever correctly on our 4720). Please HELP
 

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Put a T-valve in the heater line to shut off the heat flow.

Dave
 

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Does the compressor actually turn on? You may have to check voltage at the compressor clutch to see if its being enabled.
 

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Discussion Starter · #4 ·
Compressor works just right at 275 over 50 at 95%. This is all about the heat side getting into the air handler. Good idea about closing the heat side. However, setting the air valves correctly would be better.
 

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Do you think it's air related or something in the controller for the hot water valve or the hot water valve itself? I would pull and plug the hot water hose just for a test to see if it worked. If it does then troubleshoot the water issue. If that doesn't work then you know you have an air issue. Does it cool at all?
 
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I would be pulling the roof off the cab and watching the heater control valve (B) while moving the heater control valve cable (E) with the heater control inside the cab. If the heater control valve is not moving to the fully closed position, it will allow hot water to circulate through the heater core which will heat the air going into the cab.

785939
 

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When the 3x20 and 4x20 cabs first came out, there was a huge problem with the seals in the roof, has it ever been off to inspect?
 

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Discussion Starter · #8 ·
I would be pulling the roof off the cab and watching the heater control valve (B) while moving the heater control valve cable (E) with the heater control inside the cab. If the heater control valve is not moving to the fully closed position, it will allow hot water to circulate through the heater core which will heat the air going into the cab.

View attachment 785939
I would be pulling the roof off the cab and watching the heater control valve (B) while moving the heater control valve cable (E) with the heater control inside the cab. If the heater control valve is not moving to the fully closed position, it will allow hot water to circulate through the heater core which will heat the air going into the cab.

View attachment 785939
Thanks. I had assumed, incorrectly, that this was a heat pump issue, where the flow is reversed for heat or cool, just like the HVAC systems used for homes. I had no idea that heat came from the coolant system. Next time I pull the cover, I'll run through the steps, and see in we can get the AC working. The wife is from Kansas, BTW, and running the 4720 in summer in Texas is hotter than hell. Probable just the same for you. She will appreciate getting this fixed.
Ted
 

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Thanks. I had assumed, incorrectly, that this was a heat pump issue, where the flow is reversed for heat or cool, just like the HVAC systems used for homes. I had no idea that heat came from the coolant system. Next time I pull the cover, I'll run through the steps, and see in we can get the AC working. The wife is from Kansas, BTW, and running the 4720 in summer in Texas is hotter than hell. Probable just the same for you. She will appreciate getting this fixed.
Ted
The system used is exactly like those used on a automobiles, no difference.
 
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