4430 A/C system pressure

Just got a 4430, not blowing cold air, just a tinge of cold. The low side pressure is about 85 psi. Its 85 degrees and about 65% humidity. 85 psi just seemed really high. Should i add freon or whats the deal? Thank you

(quoted from post at 18:23:59 09/05/12) Just got a 4430, not blowing cold air, just a tinge of cold. The low side pressure is about 85 psi. Its 85 degrees and about 65% humidity. 85 psi just seemed really high. Should i add freon or whats the deal? Thank you

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robably not. Adding will raise both high & low side pressures. What is high side reading?

is the clutch running....that sounds like the pressure when the clutch is kicked out and system is equalized?

is the compressor running or not ? You need to know the hi side pressure also. If the compressor is running and you have 85 psi on low side you either have way too much freon in it already or an expansion valve problem if thats the type system. On an 85 degree day with compressor running I would expect around 35 psi on low side and 225-250 psi on hi side depending on humidity and airflow on condenser, low side will creep down as interior cools. If you dont have guages to read both sides, take it to someone who does, or you may have a can blow up in your hand if you try to add more freon.

I can jump the compressor and get cold air. I charged it up to
about 35 psi but when i hook up the positive wire that originally
came to the compressor i get nothing. Compressor doesnt kick
on and it stay up at that 80 psi number. Where do i look from here?

I can jump the compressor and when i do the compressor kicks on and pressure goes to 35 psi on low side and levels out. My problem i think is somethin to do with the hot wire going to the compressor. For some reason the compressor wont kick on when wired into the tractors system. Is there a switch somewhere i need to examine?

Sounds like you're getting a static pressure reading. Compressor engagement is based upon proper inputs to the controller. Usually automotive compressors run about 100 psi static pressure and engage only when proper inputs are recieved to the controller like engine temp not too high, rpm within limits and A/C pressure not to low or high. On most automotive units if you jumper 87 to 30 at the relay and the compressor engages you know the supply side or power side of the circuit is good. Hope this helps. Gerard

In looking at the parts breakdown for the main wiring harness in jdparts.com it shows a thermostat switch wired in between the compressor and the cab. My system is r134a and I dont have this thermostat switch. Is this my problem?

here is the link to the parts breakdown.

http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet?search=model&model=4430

I dont have number 30

Check the therostat switch it controls the compressor, also check the connection where the harness comes down the right front cab leg

You are reading the static pressure with the compressor not running. If it has been changed over to R-134 then pulling down to 35 PSI when it is 85 degrees means your system is low on freon. Fix this after the wiring issue.

You need to find out why you are not getting the cab wiring to power the AC clutch before addressing the freon issue. Your system basically works this way. The switch powers the cab relay which powers the accessories: Fan, radio, wipers, AC system etc. So if the accessories are working then the cab relay is working. Now you need to check if you are getting power to the AC thermostat control in the cab roof. IF you have power to it then turn it on and see if you have power out of it. ( I usually check this out with the top cab covers/roof off. I also clean everything out up there before I do any AC work. I have had many AC/heater issues be a dirty evaporator or heater cores.) If you have power coming form the AC thermostat then check the wiring to the AC compressor. The plug at the fire wall area is known to cause problems. You will need to do some investigating to get power to the AC clutch. Yours should also have the AC thermal over load fuse in the wiring by the compressor. The part # AR 77344 number 9 in the picture. This is to protect the compressor from running all of the time if low on freon. Some one may have removed it from your system. I would put it back in if you have the old style compressor. If it is a newer one some of them don't use the thermal fuse. Have to see what part number compressor you have to be sure.

Once you have the compressor running, a clean condenser core, a clean evaporator, plus a clean cab filter you are ready to top off your freon. You really need a set of gauges that shows both the high and low sides to really do this safely.

I usually just watch the low side as the compressor kicks in. I want it to not drop below 60-70 PSI if the temperture is above 70 degrees. The high side on R134 can be in the 300-350 PSI range on a hot humid day. I usaully just add freon until I get the low side to not drop more than I want it to. I then check the sight glass to see if I have any bubbles flowing. A few right at start up is OK. Some tractors You can't seem to get them totally bubble free. I go slow on the filling. I shut the compressor off and let it equalize the system equal out every now and then. Then watch the low side as it starts back up. I have found some tractors take more freon than the books says to really cool real good. That is why I rarely use the weight method to fill a system that is part way full.

Try this stuff and let us know how you get along.

The part # AR 77344 number 9 was notorious for blowing down here where I live. JD came out with a kit to eliminate it.