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atsrmf

Indio

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Posted: 08/11/19 09:53am Link  |  Quote  |  Print  |  Notify Moderator

I could never get the engine A/C in my 1987 El Capitan to work right. It would cycle too much despite being charged, and didn't put out cold enough air. My solution? Take everything out except for the evaporator and start over.

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This is the original ugly, inefficient R-12 system. I had previously installed the auxiliary fan.

[image]

First thing was to get the fan out of the way to get at the condenser and hoses.

[image]

All the essential parts are removed, time to get busy and install the new. I kept the OEM evaporator because it would have been next to impossible to remove it without replacing too many more parts. I flushed it out with a quart of A/C solvent instead. By keeping the evaporator I could not convert to R-134a without using adapters and risking a leak. Plus, R-134a is too difficult to charge correctly and get the right amount of oil in.

[image]

I bought the biggest R-134a parallel flow condenser that I could, which is much more efficient that the OEM serpentine tube style.

[image]

New R-12 compressor. This was a lot of fun to replace, I had to remove the left front tire and splash panel to gain access.

[image]

New condenser in place. While I was at it, I drilled out all of the radiator mount tack welds and replaced with bolts. Now if I ever have to pull the radiator I remove 6 bolts and it will drop right out. Before I would have had to remove the condenser to gain access, there was no way I ever wanted to do that again!

[image]

New filter/dryer and 2 of the new hoses.

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New expansion valve. I cleaned everything up and insulated the suction line later on.

[image]

Pulling vacuum. At first it would not hold, and I discovered that one of the fittings at the expansion valve was not centered correctly. The rest of the fittings were R-134a with an o-ring, I could not do that with the expansion valve due to the evaporator connections. Afterward it held vacuum perfectly, the needle never moved after an hour.

[image]

Charging with the first can of R-12, it took 5 cans total. I had previously added 4 ounces of extra refrigerant oil and UV leak detector. The 150cc of oil in the compressor was not enough for the entire system, around 8 ounces total was recommended.

[image]

Everything is back together and working well. I can't imagine what an A/C shop would have charged me to do this! With a motorhome you had better be able to use tools or have a lot of money. I prefer using tools.
This is my first attempt to replace an entire A/C system in any vehicle. If I can do it so can you.
The engine is a Ford 460, which doesn't slow down at all with the A/C on.
Another big obstacle was getting the correct belt and installing it. Whoever owned the RV before I did installed the wrong type of belt (cog), and installed it in such a way that the belt would shred after just 2,000 miles. This is because the tensioner was installed wrong and bent the belt backward, rather than keeping the groove inward. I replace the tensioner bearing while I had it out, one less potential headache prevented for just $18. The engine has 4 belts, all are new and the correct ones.

* This post was last edited 08/11/19 10:44am by atsrmf *   View edit history

olfarmer

Iowa

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Posted: 08/11/19 10:38am Link  |  Quote  |  Print  |  Notify Moderator

That was a big job but you did well. Congrats on doing something most people would not even try!


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crawford

Dandridge Tenn.

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Posted: 08/11/19 10:45am Link  |  Quote  |  Print  |  Notify Moderator

You got me you said you got 134a with o rings but put in the first can of R-12 ??


Change from a c class to a A class Georgetown 07 triple slide

atsrmf

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Posted: 08/11/19 10:51am Link  |  Quote  |  Print  |  Notify Moderator

The condenser, hoses, compressor, and filter/dryer all had R-134a fittings, which are compatible with R-12. Only the evaporator retained the R-12 fittings. You cannot use R-134a in an application where there are R-12 fittings, or it WILL leak.

atsrmf

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Posted: 08/11/19 10:59am Link  |  Quote  |  Print  |  Notify Moderator

Olfarmer- I did this myself because I have no confidence in most technicians today. No one would have taken the time or dedication to do it right, and either way it would have cost $thousands more, I have about $850 invested.
With the money I saved I could afford a mistake or two, fortunately I didn't make any, and now I have a vacuum pump for future use.
There's enough information at my fingertips that I can learn anything that I want. I also took a class in HVAC in college, that helped.

RLS7201

Beautyful Downtown Gladstone, MO

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Posted: 08/11/19 12:20pm Link  |  Quote  |  Print  |  Notify Moderator

atsrmf wrote:

The condenser, hoses, compressor, and filter/dryer all had R-134a fittings, which are compatible with R-12. Only the evaporator retained the R-12 fittings. You cannot use R-134a in an application where there are R-12 fittings, or it WILL leak.


Could you explain this further? What is the difference in a tub "O" ring fitting for R12 or R134A, other than the material the "O" ring is made of?

Richard


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atsrmf

Indio

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Posted: 08/11/19 12:30pm Link  |  Quote  |  Print  |  Notify Moderator

R-134 rings are green and can be used with either refrigerant. R-12 rings are black and can only be used with R-12. As far as I know, black o-rings aren't made anymore.
The o-ring acts as the seal, or gasket, in the fitting. Tightening the fitting does not improve the seal.
Flare fittings depend on 2 metal surfaces mating to make the seal, therefore the connection has to be tight. This makes it more prone to leakage.
R-134a works on higher pressures, and the molecule is smaller, therefore the seal must be better than R-12. ALL R-134a fitting are made for o-rings.

atsrmf

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Posted: 08/11/19 12:33pm Link  |  Quote  |  Print  |  Notify Moderator

Note the photo showing the expansion valve. The black box holds the heater core, diverter doors, thermostat, and evap coil. That unit costs about $900, which would double the cost of my repairs. $900 would buy a lot of R-12 (or beer), so I could not justify the expense.

RLS7201

Beautyful Downtown Gladstone, MO

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Posted: 08/11/19 07:39pm Link  |  Quote  |  Print  |  Notify Moderator

atsrmf wrote:

R-134 rings are green and can be used with either refrigerant. R-12 rings are black and can only be used with R-12. As far as I know, black o-rings aren't made anymore.
The o-ring acts as the seal, or gasket, in the fitting. Tightening the fitting does not improve the seal.
Flare fittings depend on 2 metal surfaces mating to make the seal, therefore the connection has to be tight. This makes it more prone to leakage.
R-134a works on higher pressures, and the molecule is smaller, therefore the seal must be better than R-12. ALL R-134a fitting are made for o-rings.


What I was questing was your statement "You cannot use R-134a in an application where there are R-12 fittings, or it WILL leak."
Why won't R12 fittings work with R134A?

Richard

atsrmf

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Posted: 08/11/19 08:00pm Link  |  Quote  |  Print  |  Notify Moderator

R-134a works on higher pressures, and the molecule is smaller, therefore the seal must be better than R-12. ALL R-134a fitting are made for o-rings.

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