7040 A/C question
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=187994
Printed Date: 18 Jul 2025 at 10:11pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 7040 A/C question
Posted By: Red Bank
Subject: 7040 A/C question
Date Posted: 01 May 2022 at 3:29pm
| I have installed the sanden compressor and had to remove the old manifold from the A6 compressor. The new R-134 fittings screw onto the fittings on the manifold. The question I have is the manifold has valves that will shut off the ports for the fittings and or the ports for the hoses. I assume that pulling a vacuum I will need the valves set in the middle to draw vacuum from the hoses and the compressor? Also I am under the impression this set up was used to allow a compressor change without removing the freon? So after vacuum and recharge I need to open the valves up to allow full flow for the hoses and shut off the ports for the fittings? Sorry for the questions my experience with R-12 systems is limited and I don’t recall seeing this arrangement in the past. |
Replies:
Posted By: plummerscarin
Date Posted: 01 May 2022 at 4:35pm
| Just did the same thing on mine. I believe you are correct as that is the experience I had with mine. There is a leak however, through the high side side stem. Found with fluorescent dye. I don't know if these can be repaired so will just live with it. The service manual I have for the original R12 system indicates recharging annually can be expected. Hasn't been warm enough to run the system for final check of operations |
Posted By: Red Bank
Date Posted: 01 May 2022 at 5:06pm
|
Have you tried to locate a new manifold? I have googled A6 compressor manifolds but can’t find one like I have. Usually if you only have to add a pound of Freon once a year I don’t consider that too bad of a leak but after paying $349 for a 30lb tank of R-134 last week I am rethinking my acceptance of Freon leaks. I bought a kit that replaced the compressor, all the hoses, the expansion valve and I went ahead and replaced the condenser. I haven’t pulled a vacuum yet but I hope the evaporator is ok. |
Posted By: Michael V (NM)
Date Posted: 01 May 2022 at 5:30pm
|
Red bank, yes to all your observation for the service valves on the A/C, closing the valves allowed a compressor change without losing all the freon, and only had to evacuate the new compressor Mid-position is for evacuation, checking pressures, and charging fully back seated is 'run' if the valves are good and seated, they shouldn't leak around the stem, there may be some leakage when in the mid and closed, but should be minimal, in the back seated run position, I don't think they should leak, as that is a pretty good seal... but,, I have been told that 134 molecules are smaller than R-12 molecules,,,so,,, they could leak out of smaller places |
Posted By: plummerscarin
Date Posted: 01 May 2022 at 7:24pm
| I have two others. One on a 7060 and the other a 7045. The ports are oriented in a different position so elected not to use them. Maybe not critical but if I convert them, will need for those applications. |
Posted By: HudCo
Date Posted: 01 May 2022 at 9:18pm
| pull a vaccum let it sit for 24 hour with the gauges hooked up if tis lost an inch of vaccumm the next day you have a leak the price off r 134 has went nuts.check your presure tempeture chart so that you can tell your charge and if it is working right at your ambiant tempeture |
Posted By: Red Bank
Date Posted: 29 May 2022 at 9:01pm
| Got to run the tractor today and wasn’t impressed with the a/c. It seemed kinda cold coming out of the vents but didn’t cool the cab like I thought it would. It was 80 here today and I was cutting hay. I thought I checked the drains up top but evidently I didn’t because every turn I got a nice shower falling out of the filter housing. I don’t know if I have too much Freon or not enough. I charged it at 1.60kg which is the upper end of what was recommended by the company I bought the a/c parts from. |
Posted By: DrAllis
Date Posted: 29 May 2022 at 9:07pm
| Take one of the heater hoses and fold it over and tie a zip tie on it to shut off any possibility of hot water getting to the heater core. Just do it, |
Posted By: Red Bank
Date Posted: 29 May 2022 at 9:10pm
| I had replaced the cab and when I removed it I cut the heater hoses and coupled them together. I was going to replace the heater hoses but I needed to get the tractor out of the shop and cut hay. So the heater core has nothing going through it. |
Posted By: Joe(TX)
Date Posted: 29 May 2022 at 11:11pm
|
The calves do not allow the change of the compressor. They allow everything else to be changed. ------------- 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 |
Posted By: SteveM C/IL
Date Posted: 29 May 2022 at 11:13pm
WHAT????
|
Joe(TX) wrote:Posted By: plummerscarin
Date Posted: 30 May 2022 at 12:08pm
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I think he meant "valves"? Charge pressure is relevant to ambient air temperature. Have you put a gauge on it? Ran mine today. Not freezer cold in there but satisfied was cooler than outside. I still need to get the gauges on to check it. There is a lot of glass to overcome and leaking door and window seals wont help. What are your expectations? Hanging meat cold or cooler than outside? |
Posted By: Red Bank
Date Posted: 30 May 2022 at 12:29pm
| Really wasn’t sure what to expect, I would love hanging meat cold but the only cab I can compare to is a friends Kubota and it wasn’t really all that cool. Cool enough not to open the door and windows but maybe 8 degree difference between inside cab and outside. It was 80 yesterday with typical NC humidity so it’s a lot for the a/c to overcome? |
Posted By: DrAllis
Date Posted: 30 May 2022 at 5:46pm
| Your tractor is of an age that the whole evaporator isn't covered by anything other than the rooftop. The black belly models had a piece of tin that covered all that up under the roof to seal things up. I would think throwing a old piece of carpet or cardboard over that area and covering it with the rooftop could improve your cooling capacity. |
Posted By: Red Bank
Date Posted: 30 May 2022 at 6:42pm
| Ok I will try that, when I took the roof cover off to paint it I wondered why there was a feed sack up there. |
Posted By: plummerscarin
Date Posted: 30 May 2022 at 8:15pm
| On that note, I have put 3" thick layer of rock wool over the operator area and and ¾" thick foam over the the evaporator and fan. There was foam in both this and the 7060 I have. Do not know what was factory applied if anything but certainly can't hurt. |
Posted By: plummerscarin
Date Posted: 30 May 2022 at 9:44pm
|
Another thing I've noticed is it seems that these are unable to recirculate cabin air only. IIRC the 200 cab has a door you can close to stop outside air from Being drawn in where as these 7XXX cabs do not have that feature? I think it would if were able to not blend outside air |
Posted By: Red Bank
Date Posted: 30 May 2022 at 10:15pm
| That’s an idea also, when I take the roof cover off I will study on shutting the outside air off. |
Posted By: plummerscarin
Date Posted: 29 Jun 2022 at 10:02pm
|
A little follow up today. Had a 89 degree ambient temperature and hooked the 7040 to the baler to finish first cut. Checked pressures on the compressor. Low side seemed a little low as compared to the chart but didn't have more on hand to add. Took along a thermometer and it showed cab temperature at 75. Perhaps a little warm for some but I was comfortable and stayed out of the dust   Measurement taken with fan on high and engine speed at 1000 RPM |
Posted By: tbran
Date Posted: 29 Jun 2022 at 10:19pm
|
On a 90 degree day, the high side is about right - 225 is the upper limit. Your low side is too high. Should be below 20 on 7000 series. To check your expansion valve , turn blower on low and close the door. The low side should go down to less than 15 and the compressor should kick out - if it doesn't you have an issue of air flow to and or from the evaporator. Sucking in hot outside air due to the issue Doc stated. You mentioned service valves- yes they should be back seated - turned all the way out. This will prevent leakage thru the service ports. One final check - take the high side to 220 and see what happens. see if the low side goes below 20. IF the system is operating correctly - the low side on a really humid day might have frost on it. ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: steve(ill)
Date Posted: 29 Jun 2022 at 10:29pm
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tbran... is the pressure on this tractor different than what is expected on a truck ? With R134 in the system, i normally like to see about 35 psi on the low side and 240 or so on the high side... Temp out of the vent should be maybe 45 - 55 degrees .............. all on a 90 degree day.
------------- Like them all, but love the "B"s. |
Posted By: dp7000
Date Posted: 29 Jun 2022 at 11:24pm
| I just put a new Sanden compressor and some new hoses on my 7000 black belly. Pulled vacuum 2 hours, then charged - 50 lbs low side shows 200 high side on 90+ day. It’s nice and cold. Best air conditioned tractor I have now. |