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RV A/C problem


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jim427
User

Jul 4, 2020, 10:30 AM

Post #1 of 18 (326 views)
  post locked   RV A/C problem  

I'll say up front I'm not an experienced A/C guy, but I'm learning. I have an RV that the dash A/C was working when charged with Freon, but had a Freon leak and would leak down pretty quickly. I finally found the leak which was the pressure switch. This was complicated by the fact that the pressure switch and expansion valve were housed inside the evaporator box. After I got the evaporator box out of the vehicle I took it to an A/C shop and had it leak tested and they found the bad switch. While I had it apart I thought it was a good idea to replace the expansion valve as well since it was such a pain to get to. After putting the system back together I vacuumed it down over night and it lost no pressure so was good to recharge. It is a 2.8 lb system and I put 38 ozs of Freon in it. The compressor clutch comes on and my gauges read 60 lb low and 375 high, and at no time during the charge process has it blown cool air. After about an hour after shutdown my gauges have equalized at 100 lbs each. While the compressor is running, the line going into the evaporator is hot and the line coming out is only a little cool not cold. The dryer is also hot to the touch. I was told by the A/C shop that the new expansion valve might be bad, so I tore it all apart and replaced it,,.....exact same results. Since it was working before except for a leak, I keep coming back to that expansion valve. Is it possible that they are giving a valve that is not the proper one for this system even though it looks identical? I still have the original and my only thought at this point is to put it back in and see what happens.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 4, 2020, 11:00 AM

Post #2 of 18 (315 views)
  post locked   Re: RV A/C problem  

RV? Might help what drivetrain it is and if OE front part of the thing.


For now seeing 60/375 suggests way over charged but you had a # to go by. Please just clear up what 2.8 Lbs means? 2X 16oz + 8oz or 80% of the next pound? That's not common to me to post it that way on a sticker it really should have being an RV alterations would be the norm.


Was this first intended for R-12 refrigerant (Freon) or are you using 134a the most used since swap of 1993. RVs can be around for decades on end would help what we are dealing with.


For now overcharged and or just no adequate air flow also pressures only don't mean at idle should be raised to about 1,500 or so with a temp gauge in the center vent of dash plus know the temp of the air coming in thru the grille at the time you are taking any measurements or they don't add up to mean much.
BTW 375 is high enough to blow out refrigerant or real close basics for high side is 2.5 X the temp in Fahrenheit coming in thru the grille is expected,


T



jim427
User

Jul 4, 2020, 11:10 AM

Post #3 of 18 (311 views)
  post locked   Re: RV A/C problem  

This is a 1999 Fleetwood Discovery built on a Freightline chassis with a diesel pusher engine. 2.8 lbs = 44.8 ozs I never got that much in it because that 375 on the high side was too much. This is an original 134a system. Ambient air temp was 80 F. Temp out of the vents about the same.


Hammer Time
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Jul 4, 2020, 11:21 AM

Post #4 of 18 (307 views)
  post locked   Re: RV A/C problem  

Are the cooling fans working properly on this? Very important.

The pressures indicate either overcharge or a condenser problem that could be fans.

Has it ever had a compressor failure?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jul 4, 2020, 11:22 AM)


jim427
User

Jul 4, 2020, 11:39 AM

Post #5 of 18 (300 views)
  post locked   Re: RV A/C problem  

Condenser is mounted underneath between the wheels with an electric fan. I have not climbed under there to look it over. It has never had a condenser failure. Would that fan be thermostat controlled or just be on anytime the A/C is running? I have not looked at that because as I said earlier it was working until the Freon leaked out. But I will now. Thanks.
But even if it was a fan problem, I should at least have cool air for a little bit when I first turn it on shouldn't I?
I read that wrong. No, it has not had a compressor failure.


In Reply To


(This post was edited by jim427 on Jul 4, 2020, 11:47 AM)


Hammer Time
Ultimate Carjunky / Moderator
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Jul 4, 2020, 12:01 PM

Post #6 of 18 (290 views)
  post locked   Re: RV A/C problem  

The fan may have 2 speeds. At least low speed should run all the time and it may have a pressure sensor that would activate high speed if it is in fact 2 speed.
If it's one speed it should run all the time with AC on.

You would need a wiring diagram to know how the fans work.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 4, 2020, 4:04 PM

Post #7 of 18 (254 views)
  post locked   Re: RV A/C problem  

OK and IDK: This layout is quite the creation and shocked just 44.8 OZ is system capacity for a monster of the sort? Condensers for 134a are in this low capacity for HUGE are about filters get tossed with every repair as they do NOT flush out well or at all.


I also think that's the key issue despite never saw this layout would be subject to who knows what for debris, airflow problems and internal clogging still a maybe.


If you could clean where you can get at and start all over verify items are operating as intended while charging - the guess is with 12oz cans can work fine last one would be really fussy but pressures already too high.


You really need to know all temps that are where and weigh in real close to 4 of those cans PURGING air out of lines I suspect running those thru real gauges and I do.
Still - just basics of A/C it's all wrong so far. It can compress so where is it all going as it isn't getting to the right spots to behave at all.
Make triple sure that spec for the charge amount is on target if only for a dashboard area of this thing with lines that long alone can't understand the low charge weight suggest nor pressures observed so something is still all wrong lost at the moment to say or suggest more than I and HT already did some.


Just last for now: Know your gauges are correct stinks and do get thermos to place here and there with a monster like this would be all I could do this is really a car site not personally for me all that familiar with this what hidden snags exist,


Tom



jim427
User

Jul 5, 2020, 8:10 AM

Post #8 of 18 (233 views)
  post locked   Re: RV A/C problem  

Nailed it Hammer Time. The cooling fan is locked up. This morning I started it up, and for just a little bit it was cooling. Then my high pressure started climbing and it stared blowing hot air again. Climbed under and had voltage to the fan but it wouldn't turn. Now I'm on the hunt for a fan. It hangs down underneath in all the road spray, and there are no numbers or markings to go by. Just need a 15 1/2" 12vdc single speed fan. Any suggestions? Thanks again.


(This post was edited by jim427 on Jul 5, 2020, 8:12 AM)


Hammer Time
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Hammer Time profile image

Jul 5, 2020, 8:14 AM

Post #9 of 18 (227 views)
  post locked   Re: RV A/C problem  

Not all fans are equal. Be careful what you buy. Try to get a brand name off the condenser system and buy the correct fan that can do the same job as the original.

Also, don't use the AC in the meantime. It will destroy your compressor which will in turn plug up the rest of the system.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jul 5, 2020, 8:15 AM)


jim427
User

Jul 13, 2020, 6:17 AM

Post #10 of 18 (148 views)
  post locked   Re: RV A/C problem  

Thanks for the help. The fan was the problem. My gauges now read 35 low and 225 high and I have cold air. It just happened to fail while I was in the process of replacing the pressure switch and THX, and I had tunnel vision and wasn't looking for additional problems. Looking back on it I do remember a burnt smell at one point while I was in the middle of it. That was when the fan let go. But it's mounted underneath, the smell went away and I just didn't put it together. Oh well!

But I do have one more question. When I was still troubleshooting, and my high side pressure went up to 375 psi, I tried to bleed off some Freon to relieve the pressure. Except for a short burst of Freon there was nothing in the system but air. I assumed I had blown something out and once it cooled down I put it back under vacuum. It pulled down to -29 hg and held, no leaks. Where did the Freon go?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 13, 2020, 6:24 AM

Post #11 of 18 (141 views)
  post locked   Re: RV A/C problem  

This statement is making no sense at all. There is no way that you had all air in the system. Refrigerant can present itself as either a liquid or a gas, depending on the speed it is released.

If you measured the charge in the first place, then that should be the end of that subject and you look elsewhere for your problems.

If you have the correct amount of charge and the pressure climbs to 375, then you have other issues, likely with the fan.

Have you determined if the fan is 2 speed or not? Do you have the wiring diagram for the vehicle?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 13, 2020, 7:15 AM

Post #12 of 18 (134 views)
  post locked   Re: RV A/C problem  

Quote Jim: "> It pulled down to -29 hg and held, no leaks. Where did the Freon go? <"
Vacuum at real close to 29.92Hg (world average at sea level) is only holding OUT near exactly 14.7 PSI of air pressure ; Think backwards sealing. Now when "refrigerant" is inside that is VERY temp/pressure related with wild changes is in the hundreds PSI as you saw.
It's still decent proof if it holds that it also will not leak out but it sure can still. Pressures are not in the same ball park nor is molecule size that sneaks thru when air would seal!


Tom
(fixed typos - I swear the site does that? )



(This post was edited by Tom Greenleaf on Jul 13, 2020, 8:09 AM)


jim427
User

Jul 13, 2020, 7:31 AM

Post #13 of 18 (128 views)
  post locked   Re: RV A/C problem  

I certainly agree it makes no sense, and I was hesitant to even ask the question, but I'm more interested in figuring out what happened than in how ridiculous it sounds. I put 38 of 44 ounces in when I was charging the system. The pressures went high quickly so I stopped adding Freon. When I tried to bleed off Freon I got very little out before it was just air. Smelled like air out of an old tire. I thought maybe there was a high pressure bleed off port somewhere I didn't know about. I do not have the schematic, but I was able to find the correct replacement fan. The original had melted down internally and was completely locked up. That was the burnt smell.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 13, 2020, 7:34 AM

Post #14 of 18 (126 views)
  post locked   Re: RV A/C problem  

No, you did not get air. That was refrigerant gas as I already told you.

Was the fan running full speed when you saw that pressure?

PS, you posted the same response 3 times. I know the site has issues but your post goes through on the first try.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jul 13, 2020, 7:36 AM)


jim427
User

Jul 13, 2020, 7:52 AM

Post #15 of 18 (115 views)
  post locked   Re: RV A/C problem  

No. The fan had already failed by this point. It was not cooling so I added Freon. It started working but then leaked down again. It was at this point that remember the burnt smell that turned out to be the fan. I then pulled the evaporator and found the leaking pressure switch, replaced it and the THX, put it all back together and ran into the issue we are discussing now. But it is working now that I put in a new condenser fan.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 13, 2020, 8:07 AM

Post #16 of 18 (108 views)
  post locked   Re: RV A/C problem  

So you no longer have a problem?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jim427
User

Jul 13, 2020, 8:12 AM

Post #17 of 18 (102 views)
  post locked   Re: RV A/C problem  

No it is working fine now. I was just curious about what I thought was air escaping. Freon gas it is. Thanks again.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 13, 2020, 8:14 AM

Post #18 of 18 (97 views)
  post locked   Re: RV A/C problem  

OK, closing this now as solved.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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