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RJ 4020

Posted 7/15/2015 23:41 (#4682287)
Subject: JD 4440 Air Conditioner

Northeast Nebraska

My JD 4440 air conditioner quit cooling the other day or should say it didn't cool very good for a long time. I put 2 cans of 134A in still didn't didn't do anything. Brought new expansion valve and reciever dryer home from dealer this afternoon. Was going to change these 2 parts in the morning and have someone from a repair shop come out to vacum system and put in new freon. Will these 2 things solve my problem? I was told I might have too much 134A in the system already which will not let it cool also. Dealer told me 3.5 lbs of 134A and another shop mechanic said only 2.6 lbs of 134A. So who's right?

shaun3480

Posted 7/16/2015 00:02 (#4682306 - in reply to #4682287)
Subject: RE: JD 4440 Air Conditioner

Phillips Co NW Kansas

What was ambient temp and what were the pressures before and after adding the 2 cans?

ccjersey

Posted 7/16/2015 01:06 (#4682324 - in reply to #4682287)
Subject: RE: JD 4440 Air Conditioner

Faunsdale, AL

Probably not going to solve anything......

First thing is are the condenser and evaporator clean? A garden hose and a brush along with something like dawn dishwashing detergent can do wonders for these components. May need a fin comb or just spend some time with a screwdriver straightening fins on the condenser/oil cooler. Almost a requirement that the hood be raised and the condenser slid over to be able to wash it out properly

. It is easier to clean the evaporator if you lift the roof and remove the cover over the AC, but you can do some good with a trigger spray bottle and a brush reaching up from the cab after you drop the filters down. Be careful blowing with compressed air or using a pressure washer on either condenser or evaporator. Either one can flatten enough fins in a few seconds to take hours to straighten!

If those are clean, then a set of gauges to check pressures will tell a lot about the amount of freon you have in it/need to add, as well as how well the compressor is working etc..

Without a set of gauges..run the Ac with tractor engine going about 1200-1500 rpm and AC turned to max cool with fan on high....feel of the lines at back of compressor and back under cab before and after the receiver dryer. Liquid line should be warm on a hot day, but comfortable to hold. Suction line at back of compressor should be cool and sweating if you have humidity like we do. Discharge line at back of compressor should be very hot, so be cautious about touching it for long.

Edited by ccjersey 7/16/2015 01:19

JDGnut

Posted 7/16/2015 05:46 (#4682405 - in reply to #4682324)
Subject: RE: JD 4440 Air Conditioner

Waxahachie, TX

A couple other things to check after checking what others listed..

Is the compressor cycling off and on? I had a bad thermostatic switch on one the other day.. But not very common.. The dial turned but it wasn't changing the temp when the compressor turned on and off.

If you want to check to see if the expansion valve is stuck.. Take can of air duster, turn it upside down and spray the the sensing bulb for the valve.. When you spray it, watch your low side pressure, it should go in to a vacuum. (You can spray it with refrigerant too) the high side will drop just a little. if there is a pressure change most likely the valve is working... If it won't pull all the way into a vacuum, you could have a bad compressor.

Also make sure the heater valve isn't leaking.. Take vise grips and clap off one of the heater lines at the back of the cab..

bellyacre

Posted 7/16/2015 06:50 (#4682459 - in reply to #4682287)
Subject: RE: JD 4440 Air Conditioner

SWMN

May need to replace lines that up through the cab post. They can rust out or wear through.

scott nelsen

Posted 7/16/2015 07:15 (#4682512 - in reply to #4682459)
Subject: RE: JD 4440 Air Conditioner

Leeds, North Dakota

http://www.apairinc.com/shopping/?model=10827 depends on what compressor you have for Freon amount, as posted need gauges to see whats going on, agree is compressor cycling, Scott.

Rock Road

Posted 7/16/2015 08:47 (#4682696 - in reply to #4682287)
Subject: RE: JD 4440 Air Conditioner

w/c Illinois

There should be a sight glass on the receiver/dryer. It may still be covered with a small piece of tape that protected it from paint during the manufacturing process. If the tape is gone, the glass will be covered with dirt and dust. It might also be in a position where you need a small mirror to look into it and/or a light to shine through the back side. All of that to simply say that if you have bubbles in the sight glass with the system running and stabilized, you are not overcharged with refrigerant.

shaun3480

Posted 7/16/2015 13:10 (#4683102 - in reply to #4682696)
Subject: RE: JD 4440 Air Conditioner

Phillips Co NW Kansas

I was told the bubble theory does not work with 134. The sight glass merely tells you that you are circulating refrigerant.

ccjersey

Posted 7/16/2015 22:05 (#4683994 - in reply to #4683102)
Subject: RE: JD 4440 Air Conditioner

Faunsdale, AL

It works just fine, but you will get better performance on converted automotive R12 systems if you don't charge it until you completely clear the sight glass. I think the 134a really needs a bigger condenser and evaporator than R12. Seem to get the coldest air when low side runs about 22 psi. This is most noticeable on orifice tube systems with a low side switch controlling the compressor clutch. These are very sensitive to overcharging. Also note that many of the low side switches are adjustable. if you take the wire plug off, there is a screw between the prongs of the switch to adjust the cutout pressure.

Expansion valve systems experience a much slower degradation of performance as you overcharge. Essentially as you overcharge it, you are filling the condenser with liquid refrigerant which can be subcooled, but this is a minor refrigerating effect in the whole system compared to the major effect of condensing and evaporating. Usually you want to have there be just enough refrigerant in the system that there is enough liquid refrigerant coming from the condenser to the expansion valve to keep up with the rate of evaporation in the evaporator. With 134a in a converted R12 system, and the evaporator being a little small , it helps a little to artificially lower the temperature in the evaporator by slightly undercharging.

cact34r

Posted 7/16/2015 15:35 (#4683272 - in reply to #4682287)
Subject: RE: JD 4440 Air Conditioner

Central New York

I think to any type of self diagnosis you have to invest in a set of manifold gauges to see what the system is doing. Refrigerant (R-12, R-134, Duracool, whatever) is too expensive to test things out with. A decent set of gauges can be had for around $50.

Next step is to get your own vaccuum pump - a decent small one is around $150 and will help you do any type of work to any of your A/C systems. Lots of information on the Internet about how it works. It will save you that much in lost refrigerant if you charge a system with a leak.

If it suddenly stopped working it could be:
- compressor failure
- compressor clutch failure
- leak (pressure lost)
- plugged system after the compressor tripping the high pressure switch (dryer, expansion valve, condenser, evaporator)

I had two system repairs to make this year - a blown line on a 2394 and a plugged condenser on a 3525 (never saw that before). 2nd AIparts - they were great and had everything I needed.

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