Wow! Wonder how he keeps his evaporator from icing up?

 

yes I have a heater shut off valve...sorry if I missed that question before.

 

sorry about that...thought I gave those to you in the post...I noticed I gave you everything but the pressures.

high side was right at 200. Low side is at 40. Temp originally after charging and half way thru the next day at the vent was 41 degrees. The next afternoon though....60 was the stopping point. after several days of driving around with the A/C on...my brother came over yesterday and we checked it all out again. 58 -62 at the vent temp, and same pressures....the compressor had condensation all over it, the low side line is all nice and cold and frost on the fittings...the high side line is all nice and warm going to the codensor...

any other info needed?

 

thanks for checking out the thread...but I don't have the 134a anymore...the system was retrofitted, but we took it all apart...flushed everything and went back with Freeze12 (an R12 substitute). so I don't know how that could be the problem

 

~~ bump ~~

 

Sounds like Freeze 12, might not be the best thing. Why don't you just bite the bullet and get R-12 and do it right.

 

honestly, because I can't afford to drop $90 worth of R12 into it at a time only to find a leak or have some issue where the system has to be evacuated again. And...every A/C guy I've talked to in town tells me that its roughly the same...same effects, same pressures, same cooling temps, just $25/can cheaper.

I'm not looking to create the frozen tundra in my truck...however I do want A/C that works and cools the cab down to the point that the A/C is a better option than driving faster with the window down.

If i knew that the system was fully functional with no issues and that the $90 worth of freon would be the last $90 I'd have to spend on the A/C...then I might consider that....but that hasn't been the case to this point.


however, after getting it to cool down to 41 degrees for a day I don't think the freeze 12 is the issue here. and if I can get it back to 41 degrees...then I'm happy without blowing $90 on R12.

 

Looking at your pressures your low side is to high.

The way I charge mine is by setting up a blower to cool the engine. Then I set the idle at 1200 rpm. This will give you the pressure drop like going down the road. With R-12 I shoot for a low pressure of 32-35 psi with the fan blower on HIGH/MAX Cooling. If every thing is working right this should give you around 32 - 35F discharge temp. You high side should be around 200. With an expansion valve system, the sensing bulb controls the amount of coolant that goes through the valve. And it will keep the evap from freezing up. The key to ultra low temp is to run as close to 32F vapor temp as you can on max high speed colling. Now as the cab cools down you will more that likely lower the fan speed. This is turn will drop the air tem some more, the TXV will keep it from freezing up. Most TXV systems have a site glass to aid in charging. Normally found on the drier or the liquid line running to the cond. If charged properly you should see liquid and not bubbles under stable condition. While it is handling high heat load seeing bubbles is expected. Infact you should be able to see the txv opening and closing at the site glass and on the low pressure gage.

I do not waste freon. I always pressure test with nitrogen gas. This has a smaller molecure than Ref and will leak easier. If I get a leak I go hunting, using soap and my ultrasonic leak detector. NO ref is added if a leak is present. This may take several times to find all of the leaks. I would not use CO2, this forms with water vapor and creates acid, NOT Good.

My dealing with Freeze 12, Don't waste your money.

 

I think you have a high pressure leak some where in the low side. How about your sight glass window what's the flow look like? How many oz's. is your system suppose to hold,it should be on a label or tag.. How our you checking for a high pressure leak?. How have you been charging your system with a gas or Liquid the fast way? I had a high Press. leak and couldn't find it. So, I fill the system with what, i had ((AIR)) to about about 235-250 psi and left the gauges hooked up in place and check with soapy water spray the best do, i tighten up hoses that show a leak. I left the system filled like that over night and as sure as shxt it leaked down to 60 psi and stay at this for 4 days. I used a lip sealer on all screw on hose couplings, with out o-ring. And doubled the barred hose clamps and found the condensor leak only by putting it in a tub of water like a bike tube filled with 235 psi air . I don't think the 30 minute leak down window of time is long enough for the leak to show up...I then replaced the parts as needed, That was the end of my system leaks...my 2cents
orich

 

I had my condensor leak tested at a raditor shop. I watched them put air into it and dunk it into a pool of green colored water. I don't know how much air they put it, but it didn't show any bubbles. It worked ok when I installed it.

 

hey guys...thanks for all the answers. to answer some of the questions that were ask, the engine was cool and had been sitting for well over an hour to an hour and a half before we started charging. We started the truck, turned the A/C on the coldest selection, highest fan speed, and hooked up the gauges. did one can at a time. I cannot find anything tag or sticker or anything that shows the capacity for the freon. we added 3 cans and the pressure was still a little low (and temp at the vent a little high). added the 4th and the low side went to 40 and high side at 200. then as the freon started circulating (and it didn't take long - maybe minute or two tops)...the temp got down to the 41 degree mark. drove around with it (on one of the colder nights here in a long while) and about froze with it on...went to work the next day and it worked great on the way...went to lunch (about 85 outside) and with it on full blast, the temp wouldn't go below 58 - 60.

when I look thru the sight glass, it looks like fluid...no bubbles.

orich..not sure what you mean with a liquid or a gas... we use the standard pressurized can of freon (in this case freeze 12)...puncturing the bottom of the can with the gauges and run the liquid into the system.


we put the gauges back on over two days later and the pressures were the same...just not getting the vent temps like I had. we did have a small leak on the high side valve to the compressor when closing it - i ordered one and finally have it...will put it on tomorrow evening. so I know its leaking some there...however...if the pressures are still the same, is this small leak enough to raise the temp 20 degrees?

we replaced the condensor because it was leaking in several places. after dismantling the whole system and flushing everything with endentured alcohol, we put it all back together...new orings all the way around. any hoses that were not crimped were double clamped. pulled the vaccum to 30 and it held for over an hour....then we went to charging.

blue thanks for the advice with Nitrogen gas...and what about Freeze 12 did you have issues with?

we'll put on the new high side valve to the compressor tomorrow night and I'll check for leaks around it all...and see where we go from here.

thanks for the info again.

 

I found if you were a little low Freeze 12 worked with out any issues. But straight Freeze12 did not preform like R12. Did not cool like I'm use to seeing. Being a mix it is a lot toucher to charge.

After clean the system did you add the oil back into the system componets? Dryer 2 oz, cond 2-4oz...... I have a book that gives most of these values. These are just examples I did not look actual values up.

I always charge by pressures. I do not rely on what any tag may say. If any componet was changed the tag could be wrong. Particurilly if hoses were changed. Then the size of the r12 cans changed over the years. Started out as 16oz then 14oz, and 12oz. So # of cans may are not a good reference.

Are you seeing any indication of the Expansion Valve controlling? Like 2-3 lbs change in the low pressure change. I have seen brand new valves be stuck and not work. Did you wrap the cotton (black sticky tar) tape around the valve. Is the sensing bulb clean and tight on the suction line?

Things to do, while you are trouble shooting. Block off or bypass the water to the heater... These only have to leak a very little to run the discharge temps up. 180F beats 32F any time.

Your 40-200psi at 85F are pretty close to normal. 40 is high for the low side, I prefer the lower 32-35psi. A leaking HW control valve can easly boost the pressure to 40 and greater. If you have access to the TXV (sensing bulb) while in use, use a heat gun and watch your pressure. The low should raise and hi drop as the valve opens up.

Good luck

 

The older r12 system our suppose to be charged with gas.(Can) tapped on the top up right out comes Gas. Turn the (Can) upside down hose at bottom you get Liquid freon that goes in the compressor and can damage something in there. Remember liquid you came not compress. There is pistons in it. Also when hooking up your hoses you need to purge the air from them so that you don't push air in to your system. Let a little gas come out of the line as your hooking or screwing it on and tighten. Ware gloves and safety glasses.With the 1973 ford thermostatic switch 15-25 for low side High 180 - 225 per my book .Ambient temp. of 80* ..Liquid R-12 may be used only when charging a accumulator type system ,at the suction service port on the accumulator.

When charging keep the los side below 50 pis and the high side below 240. You can add freon gas with eng. off and when it stop going in close valve on manifold ga. When start eng run rpm to about 1200 when putting in Gas. Well got to go for now..
good luck...my 2cents.
orich

 

orich, thanks for digging out the number for the specific system. And these will deffinately kick out cold air, with 10-15F vapor temp.

 

orcih & blue...thanks so much...you both have been very, very helpful.

blue...thanks for the info on Freeze 12 vs. R12...I actually did some more "discussion" with another mechanice who I respect very much....he also says that the Freeze 12 doesn't cool as good as R12 and can be a little "finicky". We did add oil back to the compressor about 5 ounces. and we added between 5 and 6 to the line going into the dryer and condensor. we had such a hard time with the fit of the condensor and dryer that we didn't think about putting oil in it while it was easy to access...so we used the hose from the compressor to the dryer (and then condensor) and put the oil in thru the hose. (by far not the best choice or the cleanest application...but one that should have accomplished the goal.) we were told between 10 -12 ounces total for the system with 5 being in the compressor and the remaining in the dryer and condesor.

I don't have any prior experience with A/C work although my brother does and is helping me with this (they're his gauges, etc). I can comment on the TXV whether or not it is working...but will get him to read this and tell me. the black sticky tar tape that was on the TXV when we replaced it was hard to get back around it. we put it back around it best we could and then took some of the foam pipe insulation that is cut down one side...we cut a piece about 4 inches...and put it over the TXV and the remaining black tape and taped it up with electric tape. we'll check he HW control valve for leaks and block it off to see if that changes anything.

orich...in your post, you mentioned this being for a 73...but mine is a 76 - would they be the same? and I thought you always wanted to add the liquid and not the gas to charge a system?? you're saying it's opposite of that - add the gas and not the liquid??


thanks again to both of you...hopefully we can get it working like it's supposed to! I'll post back with any updates.
david