Charging Dash A/C on '93 U225

Topic: Charging Dash A/C on '93 U225 (Read 908 times) previous topic - next topic

Charging Dash A/C on '93 U225

July 12, 2012, 07:56:43 pm

I am slowly stomping out all the niggling little systems problems. This is helped by discovering that some systems that I haven't tried yet just work. We turned on the ice maker when we were at Fishhook COE and darned if it didn't crank out ice in 94-deg heat. And the trash compactor worked too.

So I fixed the dash a/c fan and patted myself on the back... then we took off late on a hot day (100F) only to discover that there was no cold air coming out of the vents. We were plenty hot when we got to Fishhook and plugged right in to 50-a and turned on both roof air conditioners (both of which worked!)

I have a recharge kit for the new a/c systems but I don't know where to look for the connectors. Front (where the fans are) or rear (where the compressor is)?

Craig

Re: Charging Dash A/C on '93 U225

Reply #1 – July 12, 2012, 08:18:34 pm

The connectors are in the front access by opening the front little doors over the grill. You might want to check for leaks before changing over to r134a as I believe the 93 had r12. There is a compressor relay that I think is behind the drivers side rear wheels, that sometimes gets corroded and does not work, it is a bosch style relay.

Re: Charging Dash A/C on '93 U225

Reply #2 – July 12, 2012, 08:26:19 pm

First question is what refrigerant you have.

Suspect OE was R12. It may, repeat may have been converted to R134A.

Mine is still R12 which cools better in a system designed for R12. I bought a case of it as they were phasing out R12. Ya, expensive at $35/can. But I have half a case left for future needs.

Brett

Re: Charging Dash A/C on '93 U225

Reply #3 – July 12, 2012, 09:13:48 pm

I don't know what refrigerant it uses but since the fittings are different I'll know if I can't put the new stuff into the system. Then I'll go looking for the old stuff.

Thanks, guys.
Craig

Re: Charging Dash A/C on '93 U225

Reply #4 – July 15, 2012, 05:46:02 pm

Well I know what refrigerant my coach uses now.... the connector is clearly R12 (compared with my pickup truck which is R134). Now the question is, "How to deal with it?"

Rules now say that R12 can not be purchased by just anyone (namely: me). I can look around town for a reasonably competent air conditioner tech who has access to R12 and ask him/her to look at it and see what's up.

It's possible that it's not low on coolant but that there is another problem (solenoid, etc.). Coolant levels seems to be the easiest problem to solve if it was R134. However with R12 the problems multiply.

At some point I thought I saw a discussion here about converting a coach from R12 to R134. I know that some issues revolve around whether the R134 will deteriorate the hoses in an R12 system and wonder if the 1993 model year is close enough to the "official" change-over to the new refrigerant that this problem might not exist. Does anyone have any insight?

I know Brett has not converted (and has his own private stash of R12 to tide him over). Has anyone simply evacuated the R12 system and filled with R134? How did that work out?

Any other solutions?

Craig

Re: Charging Dash A/C on '93 U225

Reply #5 – July 15, 2012, 06:30:18 pm

I've known people who replaced dryer, service valves with correct fittings, flushed out old mineral oil and put in 134a. I've also seen nothing more than ports changed, oil dumped out as much as possible and 134a put in. Both worked.

But first you gotta find the leak because 134a isn't cheap either, being phased out. Or take your rig to Mexico and get it charged with R12.

Edit: This is a simplified explanation. There are other things to do like pulling a vacuum on the system to get any moisture out, replacing the oil with 134A compatible and so forth. I would personally go ahead and replace the dryer and oil as those things are probably overdue for replacement anyway. There are also alternatives to R12 which are reputed to work well, propane based, but no experience with them.

Re: Charging Dash A/C on '93 U225

Reply #6 – July 15, 2012, 09:20:12 pm

Craig,

I changed a couple of cars over to 134. I just bought the Autozone kit and added a can of 134 as well as a can of 134 with compatible lubricant. One of the cans has a gauge on it so you can't put too much in.

Couple of tools that end up a lot cheaper than having it done at an ac shop:

Set of gauges. About $50 at HF
Leak detector. About $42 at HF
Vacuum pump. $100 to $150, depending on model at HF. Venturi model ($15) is available but you would need a pretty good sized compressor

There could be other issues so this does not guarantee results. I pulled my dryer off and left it in the oven on low overnight. Books usually say 3 hours is the limit to leave the system open without having to replace or oven dry the dryer. The kits I have seen say it's OK to leave the old oil in the system. Almost impossible to get it out anyway. Kits also have the new fittings to install over the old size.

Mine works OK but about 75-80% of the cooling of R12.

Got to wear goggles as a sudden spray can freeze eyeball surfaces in less than a second.

Pierce

Re: Charging Dash A/C on '93 U225

Reply #7 – July 15, 2012, 09:27:40 pm

Craig,

Both systems I did were about empty. I did not evacuate the system, just added the conversion kit R134a. If the system pressure is too low, the AC compressor is locked out and the clutch won't engage until the pressure is high enough. So, my cost was only the cost of the kit at less than $40. Just used the gauge on the can.

Pierce

Re: Charging Dash A/C on '93 U225

Reply #8 – July 15, 2012, 09:32:01 pm

Hmm... well as attractive as Chuck's Mexican alternative is, I think I'll opt for the HF method and see if it works.

Thanks you guys.

Craig

Re: Charging Dash A/C on '93 U225

Reply #9 – July 15, 2012, 09:59:40 pm

The compressor oil for R12 is NOT, repeat NOT compatible with R134. The longer the hose run (i.e. motorhome) the harder it is to completely flush the old oil from the system. That is why we have stayed with R12 in the system designed for R12 and with R12 compatible oil.

And one can still buy regular R12 from private parties. I know, that is what I did-- bought a case of DuPont R12. Ya, it was $35/can, but the dash A/C continues to work very well.

Brett

Re: Charging Dash A/C on '93 U225

Reply #10 – July 15, 2012, 10:16:38 pm

Yeah, if you can get the R12 at a price you're comfortable with it will provide the best performance of all. How many ounces of gas does it take to charge the system?

Re: Charging Dash A/C on '93 U225

Reply #11 – July 15, 2012, 11:45:18 pm

Quote from: wolfe10 – July 15, 2012, 09:59:40 pm

The compressor oil for R12 is NOT, repeat NOT compatible with R134. The longer the hose run (i.e. motorhome) the harder it is to completely flush the old oil from the system. That is why we have stayed with R12 in the system designed for R12 and with R12 compatible oil.

And one can still buy regular R12 from private parties. I know, that is what I did-- bought a case of DuPont R12. Ya, it was $35/can, but the dash A/C continues to work very well.

Brett

Brett's statement was not clear. I have no doubt that one can buy R12 from private parties, but many online sources say that the purchase would be illegal. From one source:

"The following people can only buy refrigerant found suitable for use in a motor vehicle air conditioner (for example, R-12, R-406A, R-414A, R-414B, etc.), including "small cans" containing less than 20 pounds of R-12:

* technicians certified to service motor vehicle air-conditioners

(MVACs) by a Section 609 EPA-certified testing organization

* persons who buy refrigerant only for the purpose of resale to Section

609 certified technicians, such persons must provide written

documentation (that includes the purchaser's name and address) to the

seller stating that the refrigerant is only intended for resale."

I have a stash of R12 as well, but I do have my (old but apparently still valid) EPA certification. Brett, I am not saying you are wrong, just that you may be wrong, or right but vague, or right but misleading, or wrong but not in the way you intended, or...

Matt B

Re: Charging Dash A/C on '93 U225

Reply #12 – July 16, 2012, 10:29:13 am

Matt,

I bought mine many years ago when it was obvious that R12 would be very hard to obtain in the U.S. It that time, it was legal to buy and even ship by USPS.

No idea what current restrictions are.

Re: Charging Dash A/C on '93 U225

Reply #13 – July 16, 2012, 10:46:48 am

I noticed that at least one seller of R12 on eBay was requiring purchasers who do not hold EPA certs to send an email attesting that they were only purchasing the product for resale to legally qualified EPA certified refrigeration technicians. That seems to me to be a pretty flimsy way to get around the legal requirements but the seller probably feels that it covers his a$$ (or that prosecution is unlikely).

Craig

Re: Charging Dash A/C on '93 U225

Reply #14 – July 16, 2012, 12:16:01 pm

My system was converted late nineties. I charge it and it blows cold for a day or so but even the moment it is fully charged before it leaks down it doesn't really blow all that cold. Certainly won't keep anyone not in the cockpit seats cool. I remain amazed that one can spend hundreds of thousands of dollars on a brand new coach and the A/C situation is still rudimentary. All that engine power and they aren't routinely providing decent A/C without a generator in operation. I'm sure the next big evolution in motorhome design will be adequate cooling off just the main engine.

Re: Charging Dash A/C on '93 U225

Reply #15 – July 16, 2012, 12:50:27 pm

Its called 'bus air' and you can get it on Prevost conversions.

Re: Charging Dash A/C on '93 U225

Reply #16 – July 16, 2012, 01:43:50 pm

Probably the reason FT and others do not use BUS air is that the compressors are expensive ands heavy and the HP required to run one off the engine is high. Also the charge of refrigerant is large and additional evaporators are required in different areas in the coach. Having driven tour buses the bus air in 100 degree temps is still not that great and the driver is always hot unless a separate evaporator has been installed in the cockpit. I guarantee you with a load of old ladies going to the races that you will satisfy NO ONE with the temps in the bus. The solution is ear plugs and NO COMPRENDE.

Gary B

Re: Charging Dash A/C on '93 U225

Reply #17 – July 16, 2012, 03:26:52 pm

Oh yes, Bus Air and all the happiness that goes with it. For example, my MCI had the BUS AIR when I purchased it, it consists of a 9 ton compressor, a large condenser that requires a 5 HP electric fan (95 amp @ 28 VDC) and a evaporator with a 3.5 HP fan (55 Amp @ 28 VDC).
So for all that feel having BUS Air is the way to fly, I would guess they have no or little understanding of cost that goes with that system on a 10 year old vehicle.
The alternator is 250 Amp @ 28VDC, this is a must pass test for alternator, makes the little 160 amp units look like they belong on your lawn mower.
Another reason I laugh alot.

Dave M

Re: Charging Dash A/C on '93 U225

Reply #18 – July 22, 2013, 06:02:49 pm

Bumping this rather than starting a new thread so new members can see the history.

Our dash A/C on the U225 either doesn't work or works poorly. I bought the gauges from HF and the system does have some pressure; just not enough. It's almost certainly R12 (at least the connectors are - or were until I put the adapters on them to do the pressure tests).

I know several people have just evacuated the system with a vacuum pump (which I have - and thanks HF) and added R134a but I haven't seen any reports here saying whether this was a suitable fix long-term.

Anything new?

Craig

Re: Charging Dash A/C on '93 U225

Reply #19 – July 22, 2013, 06:12:55 pm

Since you system was designed for R12, the oil used is unique to R12, etc you would be better off staying with R12 unless you are changing compressor, etc. Then, I would switch to 134A, purging the oil from all the lines, condenser, evaporator, etc.

Re: Charging Dash A/C on '93 U225

Reply #20 – July 22, 2013, 08:03:16 pm

Craig, as Red Tractor mentioned be sure to check the relay on the isolator plate behind the drivers side rear wheel. If it isn't functional the clutch on the compressor will not engage and no cold air. Easy fix and cheap if that's the problem. If the clutch on the A/C compressor is working then back to the freon problem.

Re: Charging Dash A/C on '93 U225

Reply #21 – July 23, 2013, 12:28:54 am

I have done several conversions on my vehicles that were r12. Went to auto parts store and bought the changeover kits and all worked great and were still working several years later. My pickup was still going after 8 years, so don't think it is such a big thing to convert to r134a

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