In-dash air conditioner - Worth converting or fixing?

[DaHose]

I have an older Jamboree I am breathing new life into and cost is a concern. Our in-dash air conditioner is dead and I am mulling over converting it to R134A. However, I have seen some posts comment that the dash A/C is nowhere near enough to cool the RV on hot days and that it makes more sense to just run the gen. set and rooftop A/C.

If you had a 1983 Jamboree (26'), would you bother to repair/convert the in-dash A/C to R134A, or just forget about it and use the rooftop any time you wanted to cool the rig down?

Jose

[noe-place]

Dash unit won't cool beyond the pilot/co-pilot area. DW runs the genny and roof AC when things get too hot. Let your wallet make the decision for you.

[DaHose]

Hmmmmm ..... I recall my high side was mid-high 200's. I overcharged because the valves on the compressor head are weird. It's got the old school, dual seal screw valves. You have to back off from fully closed about two turns ONLY, or it gives odd readings. I ended up at about 50 psi and bled some gas, but a bunch of oil came out.

On the very up side, the dash A/C blew nice cold air last night so I know the rest of the pieces are working. Yay!

I know oil level is important, so maybe I should just have a shop evacuate the system altogether. Then I could put in the new drier I bought, drain/refill the compressor, vacuum the system and load from scratch with fresh oil and proper gas pressure.

Jose

[spacedoutbob]

I always remembered that with R12 it was 15 to 30 on the Low Side and 180 to 210 on the High Side with 95 degrees ambient temperature.

Bob in Calif.

[j-d]

That "Dealer Air" system uses an Expansion Valve, and ours was at upper passenger side of the firewall "flange" the doghouse clamps to. All you really need to do about your charge level is see if the low side is high enough to not fall into the Freezing Range on the Temp Scale of your Low Side Gauge, and not too high. Too high will mean that your evap temp is too high. In other words (without a gauge with me to look at) somewhere in the mid-20's maybe low-30's pressure-wise. What's your high side pressure, hot day and fast idle? The more charge you have (above spec) the less cooling and the higher the high side pressure. Hopefully your high side won't be much above say 200. On our converted (R134A) "Dealer" system, we had to run it low on charge or the high side would spike. This is common on conversions, shouldn't be a problem with R12. But that low charge caused our Expansion Valve to freeze over. When they do that, they no longer cool. Wrapping it in that Press-Tite (Cork) tape solved that.

[TyroneandGladys]

FORD 1983 Bronco, Econoline E100-E350 & F100-F350 Pick Up Truck Shop Manual CD But I would run a VIN decoder to verify the year first since chassis years and coach years sometimes do not match.

[DaHose]

Hey everyone. I finally got back to looking at my AC. I determined that the system is completely sealed and there is residual pressure from R12, but it just BARELY moved the needle. So it was sealed, but basically empty. I have manifolds and tried to load refrigerant to the proper pressure. Everything I read says that 35-40 is the right pressure, so I went to 40 and it blows cold. YAY! Afterwards, I did some more looking to think about a long term change to a more efficient compressor and found a web site talking about correct R12 pressure being 25 psi low side when the compressor is cycling. Now I am worried I overcharged. I will try to hunt down a manual tomorrow, but I know the Clymers and Hanes can be iffy. Does anyone have a shop manual for a circa 1983 Econoline, or just know what the correct low side and high side pressures are for my setup?

Thanks for any help you can offer, folks.

Jose

[time2roll]

I would definately get it repaired. I would tend to go with what the shop recommended. Replace hoses too if any sign of weakness.

[DaHose]

I like to really dig for stuff when I am curious. HC based refrigerants are now in use by OEM's in production vehicles.

Document about OEM auto manufacturer using HC based refrigenrant

Apparently, Europe is outlawing R134A by 2017. That makes sense of the zeal with which producers of R134A are lobbying to keep HC based refrigerants out of the US market. Once Europe finds an alternative, it will make its way elsewhere. Australia seems to be leading the charge of HC based refrigerants for automotive use.

Jose

[crawford]

Go buy the retro kit about 40.00 or less drain out old stuff at new I know your are not to let r 12 out. I replaced at least 30 units all are still working. Or bring kit to a garage and give them the kit.

[j-d]

Actually my safety concern is an evaporator leak, flammable gas released inside tha part of the coach we occupy. It'd take a lot of facts to satisfy me that a fuel used as refrigerant isn't more dangerous than a refrigerant used as a refrigerant.

Clutch working... Well, two things. We had a Dodge with aftermarket A/C. I installed it myself and one of the scariest thing I ever did on a car project was cut a shoebox-sized hole out of the middle of the dashboard of a brand new van. Anyhow, after years and years of use, the clutch wouldn't always pop in. I installed a relay. Thermostat triggered Relay, Relay powered Clutch. Worked consistently thereafter.

You're seeing "static pressure." The warmer the weather, the higher the static (system NOT running) pressure you will see if you connect a gauge set to the service ports. I think R12 static pressure in PSI is pretty close to ambient temperature in Degrees F. Nature of refrigerant is such that it'll display the SAME static pressure whether somewhat over full, correct charge, or nearly empty. Good thing about finding pressure is that although it may have leaked down, it's not wide open to the atmosphere. So yes, you could try to charge it up. If your friend is into HVAC, he should be able to find an "oil charge" that adds a couple ounces of oil without having to discharge and open the oil plug on the York. There are cans that contain such a charge and tools that let you add oil to the tool then use it to force the oil into the system through a service port.

[JaxDad]

Most A/C systems have a pressure sensitive safety switch to protect the compressor. If the pressure in the system falls below a certain point, the switch prevents the compressor clutch from engaging.

That doesn't mean the system is empty, just low. The fact that there was still some residual pressure bodes well for the possibility of it needing little more than a refill and maybe a little oil.

[DaHose]

So there is a new wrinkle. I moved around the wires and jumped the clutch on the compressor. It worked fine. Then I tested inside the cabin and when I switch on the A/C, the compressor engages. So the electrical looks like its working. I thought the system was totally empty, but when I started unscrewing the receiver/dryer (so I could replace), I heard a tell tale hiss of venting gas. Could that just be compressed air from when the compressor was running or is that venting sure to be some remaining R12?

Jose

[sljkansas]

Another thing to look at is the dog house cover and the seal. You'll want the seal to fir tight and either the inside and or outside of the it well insulated. We made a dog house cover for our old Dodge C and use Reflectix 4 ft. x 25 ft. Double Reflective Insulation and made the blanket to wrap the Dog house, and continued it under carpet in the cab. We (well the Wife) made a cover to dress it up. this made a big difference in the heat in the cab.

hey j-d hows thing in Fl? Pm me

[JaxDad]

The problem with using the dash a/c to cool the m/h is not the cooling capacity of the unit, the system used in the Ford chassis is capable of (depending on RPM) producing 50,000 BTU's but at highway speed, about 30,000 BTU's. that is more than double the capacity of a typical rooftop unit.

The problem is the relatively feeble fan to circulate all that cold air.

If however you open a roof vent at the very back, like the bathroom, this creates a powerful vacuum drawing the warm air back there out, and cooler air from the front back to replace it.

In our 24'er we can keep the entire m/h comfortable enough doing this even if the hottest weather as long as we're moving of at highway speed.

[DaHose]

Ok, folks. Hold on to your hats, because this post is a long one.

I just finished a few hours worth of researching and reading up on air conditioner and refrigerant type “stuff”.

What you say makes sense, Matt. I found some sites that talk about maxi frig and it really is just another brand name for HC-12a. I don't know the volume for my rig, but do I know that in my cars (I have been battling a/c issues lately) I only use 1-2 lbs.

Now for some science type stuff. I read that the self ignition temp. on HC-12a is over 1600 degrees, which is twice the heat of normal propane. HC based refrigerants are a type of LPG and burn completely clean, plus they still have the odorant that lets you know when there is a leak. As a bonus, HC-12a is made of bigger molecules than R12/R134a, so it is less leak prone. I also saw several references state that because HC-12a refrigerant is far more efficient, you can use as little as 35% of the charge required for the same R12 based system, so you use way less volume than R12. Also, people said they found that the lower volume of gas moving, results in less drag and improves mileage (we talked about that York robbing me of some mpg), so retrofitting an R12 system with HC-12a should yield a performance increase.

On the other side of the fence, R134 is both toxic and corrosive and it actually is highly flammable when mixed with the oil inside your compressed system. R12 also burns, but it also breaks down into phosgene compounds which are HIGHLY toxic.

The biggest risk everyone seems concerned about is the condenser full of LPG in the front of your vehicle rupturing in a crash. However, unless there is an open flame at that point, it will disperse almost immediately. If it does ignite, it will cause a great big puff when it ignites and the remaining compounds are rendered inert. The worst case would be a sealed system caught in a fire and getting hot enough to burst. That could be quite ugly, but I was unable to find a single reference to studies documenting HC refrigerant fire/explosion rates in automotive applications. Mind you that an R12/R134A system could also burst when exposed to fire. That would also VERY bad and the remaining compounds would be highly toxic.

I looked, but couldn’t find anything about commercial based systems or recalls of HC refrigerants and those applications have been using HC based refrigerants for a very long time.

I understand the concern over putting some highly flammable gas into your A/C and having it near your SMOKING hot engine parts, but I also understand the argument for why HC-12a based refrigerants can be used safely. Canada allows the use of HC-12a in production automotive systems (they are safety crazy like we are) and I don't find any statistics or numbers one way or the other about its safety record in the auto industry. In the USA, the “legality” of using HC based refrigerants varies, but it is legal in California. So if we are using it here in Ca. and you don't hear about constant class action lawsuits or recalls, that is a strong indicator of a good safety record.

I will keep digging for more information, but HC-12a really does look like an ideal refrigerant that can replace whatever you are running and is compatible with whatever parts and oil you have in your existing system.

Jose