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chuck linn 
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Joined: 13 Dec 2012
Location: ky
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 Topic: 7020 airconditioner
Posted: 04 Aug 2018 at 6:22am |
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Changed dryer expansion valve and compressor last year tractor does not get cold in cab only slightly cools low side runs about 28lbs at about 1500 hundred rpms good airflow on blower no high side reading broke gage what else could be problem thanks for any help
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DrAllis
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Joined: 12 Sep 2009
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Posted: 04 Aug 2018 at 6:43am |
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Fold over/pinch off at least one of the heater hoses to be absolutely sure there isn't ANY hot water getting upstairs. I do not like vice grips on a hose....fold it over first.
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Roscoe62
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Posted: 04 Aug 2018 at 11:05am |
My expansion valve got plugged with "gunk" after a recent repair, and stopped working....
- Roscoe
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bradley6874
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Posted: 05 Aug 2018 at 10:01am |
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Did it work last year after repair ? Get your gauge fixed with out the high side pressure your just guessing search r134 pressure chart that pressure says way low charge unless it's 65 degrees outside lol
Edited by bradley6874 - 05 Aug 2018 at 10:13am
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You can wash the dirt off the body but you can’t wash the farmer out of the heart and soul
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Joe(TX)
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Posted: 05 Aug 2018 at 5:57pm |
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Did you also change the dryer? It needs to be replaced if you had a compressor problem.
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1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A
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chuck linn
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Location: ky
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Posted: 05 Aug 2018 at 7:43pm |
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Changed compressor dryer and expansion valve flushed system too heater unhooked also
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Hurst
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Posted: 05 Aug 2018 at 9:24pm |
Did the system ever cool properly after the repair? Does the suction hose sweat at the compressor after running for a few minutes? That's an easy "get it close" way to charge and know the system is working correctly. How much r134a did you charge the system with? Even with 134a, you should be getting into the 40's on vent temperatures if you are close on charge. If you get your high gauge fixed, let us know what the reading is on the high side, that will shed a lot of light on the problem.
Hurst
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1979 Allis Chalmers 7000
5800 Hours
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bradley6874
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Posted: 06 Aug 2018 at 11:09am |
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You can wash the dirt off the body but you can’t wash the farmer out of the heart and soul
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bradley6874
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Posted: 06 Aug 2018 at 11:10am |
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Hope that helps chart is from AC pro page for cars
Edited by bradley6874 - 06 Aug 2018 at 9:38pm
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You can wash the dirt off the body but you can’t wash the farmer out of the heart and soul
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wekracer
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Posted: 06 Aug 2018 at 3:21pm |
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Bradley. Are you sure that chart is for automotive application. On my tractors and combines I’m typically in the 20-30 pound low pressure range with the high pressure as shown on the chart 85-95 ambient temp.
I’m no expert by any means. I am however in the middle of installing all new ac on the 8010 and have been doing more research than in the past
Edited by wekracer - 06 Aug 2018 at 3:24pm
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Hurst
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Posted: 06 Aug 2018 at 5:51pm |
I feel like the older tractors tend to run a little more of a spread to get good cooling, maybe because they don't have as high efficiency condensers. At the end of the day, knowing the low side is 20 psi doesn't mean a whole lot without knowing the high pressure. If you have 20 on the low side and 300+ on the high side, you likely have a blockage or stuck expansion valve. You could have 20 on the low side and 100 on the high side, meaning you are under-charged. You should be able to get a replacement gauge at a good auto parts store or hvac retailer. These are expansion valve systems, so it can be very tough to charge these by just the low pressure. Additionally, I believe the automotive charts you see are designed for a car that is idling, and a car is a little different set of conditions than a tractor (more airflow at idle, compressor shaft speed probably a little higher, etc).
Hurst
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1979 Allis Chalmers 7000
5800 Hours
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Brian Jasper co. Ia
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Posted: 07 Aug 2018 at 6:04pm |
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Normal low side pressure for a thermal expansion valve system using a thermostatic switch is 10-15 psi. The rule of thumb for converting an R-12 system to R-134A is 80% of the R-12 capacity. Back when retrofitting automotive systems was fairly popular, I always started out at 50% and then sneak up on what the system liked by adding small amounts until the low side just started getting good and cold with the blower on high.
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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chuck linn
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Posted: 08 Aug 2018 at 9:34pm |
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Found overheat switch leaking on back of compressor ordered new switch and oring will install tomorrow pressure was 35 on low 190 on high side cooling about 55 degrees temp on outside 80 degrees didn't seem cool enough but line really sweeting
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Hurst
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Posted: 08 Aug 2018 at 10:53pm |
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Did you draw a vacuum on the system the last time you worked on it? Which line is sweating? If it's the suction line between the evaporator and compressor, that is normal. When you say 55, is that the temp in the vent? Is the compressor cycling on you? Have you cleaned the evaporator core? The lines sweating and pressure readings lead me to believe the refrigerant cycle is working properly, but for some reason you are getting poor heat transfer at your evaporator coil or the all to common heater core warming the air, but you said that was taken care of (hopefully you have a ball valve on the thermostat housing to cut it off during the summer)
Hurst
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1979 Allis Chalmers 7000
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Hurst
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Posted: 08 Aug 2018 at 10:55pm |
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Oh, and how much refrigerant did you put in when to put the system together?
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1979 Allis Chalmers 7000
5800 Hours
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wekracer
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Posted: 09 Aug 2018 at 6:14am |
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On an 80 degree day I would expect my high pressure to be 215-225 and the low between 20-25 and not over 30.
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Hurst
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Posted: 14 Aug 2018 at 12:31pm |
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Did you ever find out your problem on this? I am having the exact same issue on my 7000 since I put the new Sanden conversion kit with a new expansion valve and receiver/drier. I charged it and I'm getting low 60s at the vent temps (about 15 degree drop), but my suction line is sweating heavily even frosting over a little at the compressor. I am pretty sure my external equalizer is bypassing refrigerant straight from the expansion valve to the evaporator outlet, so little cooling is happening in the evaporator. My pressures were all normal, maybe a tick low on the high side for the temperature, but the give away is my evaporator line is just a little cool until you get within a couple inches of where the external equalizer screws on (this is the small tube that comes from the expansion valve and connects onto the line leaving the compressor). If you are still chasing this problem, pop your cab top and see if you have a slightly cool line leaving the expansion valve and a very cool valve at the external equalizer fitting.
Hurst
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1979 Allis Chalmers 7000
5800 Hours
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chuck linn
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Posted: 14 Aug 2018 at 7:53pm |
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Changed expansion valve again now getting 50 degree air instead of 60 same pressures 30 on low 150 high side still could be colder but liveable
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Hurst
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Posted: 14 Aug 2018 at 10:12pm |
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Where are you getting your expansion valve? I wonder if we're getting them from the same place or supplier and it's a based batch? I'm getting mine from All State Ag Parts. I'll check the package on the replacement to see who the supplier is, but I think out may be AP Air who is the supplier of their conversion kits. I may reinstall the old expansion valve. It would give me low 40s/high 30s at the coil. Only reason i changed it was for three compressor warranty. Is your suction line still really cold?
Hurst
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1979 Allis Chalmers 7000
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wekracer
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Posted: 15 Aug 2018 at 4:47pm |
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I’m interested in this. I have a new compressor, hoses, expansion valve and dryer from ap air that I plan on putting in the 8010 this weekend
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K bockting
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Posted: 15 Aug 2018 at 9:36pm |
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Just replaced a/c compressors on both my 8010, s this summer.
Used Sanden replacement on one and A6 replacement on the other both from AP air . Cools very good,
everyhing has to work correctly.
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Hurst
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Posted: 16 Aug 2018 at 8:58am |
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Looking at the packing list, I think my expansion valve was a different supplier than AP Air. I bought the compressor conversion for my 7000 and everything mounted up great and was super easy to put together. I'm sure once I get a good expansion valve in, it will work great. I am waiting on the replacement. When I get that, I'll pull the old one and see if you can feel the leak through the external sensing line by blowing through it or if it really takes some pressure to get it to leak. I know my old one worked great and the old compressor just lost compression on a piston or two, so no debris in the system, and the old one will not leak out of the sensing line with me blowing through it.
Hurst
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1979 Allis Chalmers 7000
5800 Hours
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fourthgeneration
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Posted: 16 Aug 2018 at 11:32pm |
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When I am charging an AC system I vac it down then charge it to 200 psi with nitrogen to leak check it.
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Hurst
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Posted: 17 Aug 2018 at 2:19pm |
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The problem I found is not an external leak. In fact, this system passed a pressure test and held under 1000 micron vacuum for a couple of hours. The problem is an internal leak in the expansion valve that is allowing the condensed refrigerant to be metered off into the suction line back to the compressor instead of the evaporator, and as such, the temperature sensing bulb right next to the external equalizer fitting is thinking the evaporator is flooding due to the cooling of the line at this fitting, and consequently closing off the expansion valve, which just exacerbates the problem by leaving the only path for the condensed refrigerant as through the expansion valve sensing line. I don't think it is a very common problem, especially on automotive or off-road applications. I stumbled across it reading on problems with residential and commercial systems that exhibited the same symptoms.
Hurst
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1979 Allis Chalmers 7000
5800 Hours
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