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Topic: How much freon R-12 for the dash air on a 1994 U-240? (Read 1904 times) previous topic - next topic

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #20 –
In the never-ending quest for more tools, I bought a Harbor Freight A/C manifold with gauges yesterday. This manifold comes stock with R134a quick-connectors so I put a pair of those over my R12 connectors and connected everything up. Pressures on both sides were about 95 (not sure what it was ... psi?) and paperwork with the manifold said that both sides should be "about the same".

I think looked around for some idea of what the pressure gauges should be measuring and came up with a blank.

So I still have R12 in the system... my question is what pressures should I be measuring?

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #21 –
Craig,
In my (limited) experience, the suction side should be lower when the compressor is running. It is the differential that makes for the expansion and thus the heat extraction. In cars that I have refilled (using a high and low side gages), when it was up to spec the low side was typically somewhere around 25 to maybe 40psi and the high side would be around 120psi. Also the site glass would have bubbles when a little low (obviously not when empty!) and as it would take freon, the bubbles would gradually disappear. Also, the suction side piping would get very cold and the high side would get very warm. This has been on R12 systems on various makes and models of cars. No idea if the coach would signifigantly differ from that, but I would guess they would be similar. I have changed over a few to R134, without chaging the recomended components and got away with it, but it depends on the receiver dryer state at the time of the changeover. The things you will do when you are a starving musician ;D ...
I am sure that others with actual knowledge will chime in, but it has worked for me... as to the specs, I just used an automotive encyclopedia to get some generic values for the pressures that I received while taking a Volkswagon apprenticeship course...
YMMV!
Don
Quote from: wa_desert_rat –
In the never-ending quest for more tools, I bought a Harbor Freight A/C manifold with gauges yesterday. This manifold comes stock with R134a quick-connectors so I put a pair of those over my R12 connectors and connected everything up. Pressures on both sides were about 95 (not sure what it was ... psi?) and paperwork with the manifold said that both sides should be "about the same".

I think looked around for some idea of what the pressure gauges should be measuring and came up with a blank.

So I still have R12 in the system... my question is what pressures should I be measuring?

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #22 –
Don... thanks for the info. I forgot to mention that the write-up that came along with the manifold said to check first with the engine off and the pressures should be "about the same". I did not try testing with the engine running and the A/C system working yet because that was the next step and I was supposed to determine "from the owner's manual" what the pressures should be before proceeding on.

So I guess tomorrow morning I'll run the engine and ask the DW (who is busy installing tile in the bathroom) to high-idle it for a while.

Golly, this is fun!  :P

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #23 –
I went to fill mine with refrigerant thinking it was very low (my compressor did not turn on) well my gauge showed 50lbs on the low side and no bubbles in the site glass.  So I am guessing I have an electrical issue. Checked the under dash fuse and it was fine. What next?

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #24 –
Quote from: El_Dorado –
I went to fill mine with refrigerant thinking it was very low (my compressor did not turn on) well my gauge showed 50lbs on the low side and no bubbles in the site glass.  So I am guessing I have an electrical issue. Checked the under dash fuse and it was fine. What next?

My U225 has a set of 12vdc circuit breakers next to the battery box in the basement. I seem to recall that there is one for air conditioners in there somewhere. I could be wrong but you might want to check.

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #25 –
I would say that is too low considering the compressor isn't going. It could very well be too low and the pressure switch that allows the compressor to turn on is just doing its job. Most systems have a connector which you can put a jumper on to engage the compressors clutch. When I haven't been able to locate that, I have successfully just provided 12v to the A/C clutch to spin the compressor and create suction to add the refrigerant... FWIW
Don
Quote from: El_Dorado –
I went to fill mine with refrigerant thinking it was very low (my compressor did not turn on) well my gauge showed 50lbs on the low side and no bubbles in the site glass.  So I am guessing I have an electrical issue. Checked the under dash fuse and it was fine. What next?

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #26 –
Going to look now and also see if I can pinpoint that on my wiring diagram

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #27 –
Now that I am back from our first long trip. I am back dealing with no dash air (we used the Genset and roof air when needed) and really need to try to get this working before I succomb to taking it to an A/C shop.  Looking at my wiring diagram, there is a 15 amp fuse someplace in the system. In the diagram is shows close to the isolator, boost solenoid and start solenoid. Those are located on the bulkhead forward of my batteries. For the life of me I cannot find that fuse. Looks like it my be on a wire that is #87.  The one and only wire going to my compressor is very hard to get a hand on, but trying to test it with the motor running and A/C turned on there seems to be no volts, but I am not to sure if it was a valid test. I cannot chase the wire because of how it goes into a giant wire loom.

As of now, I am reasonably sure the system still has refrigerant, because the low side shows 90lbs. pressure......

My two questions are.... where is the fuse, and is there a convenient place to apply 12v to the A/C compressor clutch for a test ?

Steve

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #28 –
Steve, my unit is different than yours but I checked to see if compressor works by putting a jumper wire to the one that goes to clutch and grounding it out on something. I am sure that is what I did. My 15a fuse is one of the bus type with 2 small screw threaded connectors on it. I have one for the compressor fan too. Someone will tell you and hopefully I am correct on that test
John

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #29 –
The thing you are looking for is a 12 volt circuit breaker, not a fuse if that helps. You can test for 12 volts in that area with a 12 volt test light or a volt meter and there should be a 12 volt bosch type relay there also.

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #30 –
Got it finally, got the compressor to go and now understand this.  Fortunately the compressor clutch is just fine I think my Bosch relay is bad and will go get a new one.  However, if that is not the issue, how can I test the low pressure switch?
YAHOO, problem was the relay, put a new one in and all worked as advertised, charges it up with ENVIRO-SAFE R-134a REPLACEMENT and now have dash air again............
Steve

PS about the refrigerant:I went to an A/C shop yesterday and asked a few questions in case I could not get my system working. I asked him if he would charge with this stuff and he said NO. When I asked him why, he said it is because he does not like the stuff. OK, I asked why... he said it can burn. Well I said what is safer, fire or Phosgene gas.... no answer except I just do not like it. Then he talked about compressor oil and I told him it was compatable with any compressor oil.... still said he did not like it.  If I were to have had him recharge my system with R-12, he charges $7 an ounce or should I say $112 a pound he definitely liked that......... so I used the replacement Propane/Butane combo at $4.16 a can.  Love it......

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #31 –
Steve; on automotive work, I used to just pull the harness connection at the pressure switch and plug in a jumper wire across that connector......to simulate a call for the compressor to run.  Also, with the harness connector unplugged, you could just measure for continuity across the pressure switch contacts.....there should be continuity until the compressor sucks the low side down to create near-freezing conditions in the evaporator... then the switch should open (and the cycling starts over again when the vapor pressure of the refrigerant builds back up again)......hence the term CCOT or cycling clutch/orifice tube system.  Seems like the most common pressure switch failure mode was to fail "open" ...... (rather than fail closed i.e., shorted internal contacts).  When I  was doing automotive A/C, you could just unscrew the pressure switch and screw in a new one.......there was a schrader-type fitting in the suction line piping that would seal off the port as the switch was removed.....the new one would depress the shrader upon installation; I suppose it is still the same.  Good luck with the repair.......drivin' cool is good.  Ed S.

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #32 –
Steve... you had said that you had 90psi in the system earlier and I assume that was R12. Did you draw down that system with a vacuum pump before charging it with R134A?

Dryer change?

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #33 –
Craig,
90 was with the compressor non functioning, But I had a real cheapo gauge(now resides in my trash can) and set-up for refill. It may have been reading can pressure. When I got the compressor to run and put a high quality gauge on it had about 25 lbs @ 86 degrees. 3 cans of refrigerant brought the pressure up to 45lbs and the dash now blows cold. I did not take a vent temp, or take any readings on the high side, my new set is only for the low pressure side. 

No, I did not evacuate the system. This new replacement is 100% compatible with R-12 or R-134a and any kind of oil in the system plus the nice thing is if moisture ever gets into the system, it does not turn the refrigerant to corrosive stuff. Works out nice because I do not have a recovery system and will not let freon go free. I like to be able to do this kind of service on my own.  Leaves much more cash in the poke for travel and I get to learn my coach!

Next big projects will be new drive tires. new bulkhead bolts then the severe oxidation and worn out graphics............. We bought it knowing there would be many projects to tackle.

Ed, looks like the pressure switch is a four wire set-up, that is why I was asking about it, Two wire would be a piece of cake.  Fortunately that was not my problem....

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #34 –
Enviro-Safe, that's a nice tricky name isn't it.  Maybe safe for the environment  unless it catches fire or causes an explosion, after all it is a mixture of propane and butane according to others.  I haven't analyzed it so I'm not sure what it is.  How about a slow leak in a compartment or inside the motor home until a spark sets it off like when someone flips a switch, ignites the stove, etc.  A slow leak in your system, that's why you are installing it anyway, isn't it?  Many substances make good refrigerants, but until the invention of freon most had some other property like being flammable or poisonous.  It's legal to sell it, but it isn't legal to use it in automotive applications; probably the reason the licensed technician would not install it.  If you are going to use it, maybe you should put a label at the entrance door and test ports so that the next owner and others will know what they are dealing with.  May I be the first and hopefully not the last to wish you good luck with Enviro-Safe. 

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #35 –
Quote from: Jerry Whiteaker –
May I be the first and hopefully not the last to wish you good luck with Enviro-Safe.

My coach carries 50 gallons of propane which runs aft to the bedroom furnace and across to the salon furnace as well as to the water heater and the refrigerator. Then there is the liquid propane line that runs to the generator. Then there is the ammonia in the refrigerator itself.

I wonder how flammable R12 and R134A is.

Craig

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #36 –
As I understand it, the commercial refrigeration guys now use a refrigerant called R-420A in equipment that previously used R-12 and it is supposed to be an excellent replacement.
Regards,

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #37 –
The A/C shop I took mine to last year still had some R12 and used that.

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #38 –
Just a quick report of how the new EnviroSafe refrigerant works...... very cold is all I can say.  I am totally happy with this alternate method and I found out that this is what is used in Australia.
Cheers,
Steve

Re: How much freon R-12 for the dash air on a 1994 U-240?

Reply #39 –
Quote from: El_Dorado –
Just a quick report of how the new EnviroSafe refrigerant works...... very cold is all I can say.  I am totally happy with this alternate method and I found out that this is what is used in Australia.
Cheers,
Steve
Did you happen to try their Stop Leak?  My last charge of R12 appears to have leaked off through some tiny, unseen, hole.  And the R12 is hard to find and expensive.