Hello everyone, I have a little time today and dug into one of the projects on the list. The dash AC was not working. My son and I did a bunch of troubleshooting today. Basically narrowed it down to power makes it from the breaker, to the dash switches, out of the switch and into a pressure switch on top of this black contraption (what is it?) From there my assumption is it goes to a second limit switch on the low pressure line (see green switch with melted wire loom). Have not been able to get power there yet but even though the looming was melted the wires appear to be intact just fine. I assume something was going to be messed up there and that's why the AC wasn't working.
I skipped ahead in the circuitry and tested the AC relay to make sure it was functioning . Everything tested fine at the relay. The switched power is not making it to the relay to engage the compressor is the hang up.
At this point I'm pretty confident the system is low on refrigerant, going to get some gauges tomorrow If I have time.
We'll see one of the posts the pictures and see if you guys can tell me what the black thing is and if anyone's ever seen the pressure switch wires get hot like that and melt the looming.
One other note, the AC was worked on recently. The compressor has a sticker with a 2017 date and looks new. That black thing is newer and shiny. I'm guessing it was working recently and leaked down.
Dash airs are not very reliable and very problematic.. a lot of people don't use there's. The black thing is a dryer
Keith
I have read that some people don't use it. I would like to, running the genset while driving is not my favorite. If it's a major fix I probably won't but I want to know the issue before I just give up. It may just be low on juice and I'll be good to go with some cheap cans once and awhile! Someone obviously spent some coach bucks on the system recently. Would like to know if I can get it going!
Thanks for the reply, the dryer, okay. Something new to research.
The dryer is like a filter. It takes out moisture and dirt out of the system. The sensor
on the dryer wasn't on my Monaco. The sensor on my low side is disconnected but
I have order new high and low fittings so I will have new sensors. I don't know why
Foretravel uses three sensors. Last year my AC wasn't working and I put a can of
refrigeration and got it working and then never deeded it. This year it was completely
empty and the high side fitting was corroded so that is where the leak is.
Recently got ours going again ( burst line over engine ) and I like it. Not sure it's cheaper than running the geny but we're using it.
I would fix it again I think just cause I like to have things working.
There is a relay for the compressor under the bed and for unknown reasons PO had disconnected. I plugged back in and my finally had power. All these old Freon systems are twenty years old but can be maintained and made functional. My particular system has a restriction and operates with a excess pressure differential. I have ordered a new expansion valve and a new receiver dryer. Have to fix the evacuation machine before I can repair my own system but worth it.
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Hope they are the correct ones
Scott
We were recently traveling through New Mexico, full sun and 105 degrees outside. We had the generator running and both roof ACs going, and the interior temperature kept creeping up. While I drove, I considered the options for the future, and wondered if we needed a third AC unit.
Then it hit me! I reached over to the dash controls, turned on the dash AC, and the temperature dropped to comfortable levels. We already had a third AC!
We use the dash AC a lot when it is around 90 and under outside. I had never thought before about using it WITH the roof ACs.
Glad I fixed it!
If you can't increase air conditioning performance reduce the loads.
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I swear I'm going to buy a big roll and learn how to do it myself for your windshield
Scott
Read the reviews,mostly negative.
The dash ac will not keep up on a hot day by its self, but it is a nice add on with the roof ac's. Also when you stop for the nite the coach is already cool if you are using the roof ac..
Dryers are cheap, less than 50 bucks.
Keith
I was able to pick up some gauges this morning from O'Reilly Auto. Loaner set...which I don't totally trust were working proper.
I was able to get them hooked up, at first reading I had -10 on low and like 100 on the high side. Compressor was not firing. I now had power in and out of the dryer switch. I was skeptical of the melted pressure switch near the low port. I cut the wires and spliced together. Still no compressor... More wiring diagnosed and found the relay was wired wrong. Fixed that and compressor fired.
With the compressor running I started adding 134a. I was able to get the high side to about 195 but low side never got above 30. I would add another can, pressure would climb to 40, then I shut the valve and back to 30. I ran 8- 12oz can into it. Dash temp output was 58 degrees. Cooling but not cold.
My theory is the gauge set was leaking somewhere and would not hold higher than 30 on the low side. Could that be possible? I feel like I might have just put 8 cans into the air at this point. I've not done enough to know how it should react during fills.
Now this melted green pressure switch on the low side, is that replaceable without draining down the system? I am hoping that is screwed into a shrader valve. Can anyone confirm? Also if there is a way to test it and see if it's bad?
You should be able to shut compressor off and gauges should read the same pressure after setting a while. This will show how close they are. No clue on the pressure switch . Possibly new pressure switch would show if it was set up to open a valve on installation?
Scott
Kieth.
I respectfully disagree. On a 111 degree day recently our dash ac was keeping up if you mean blowing cold. Of course it wasn't cooling the entire coach but the drivers area was comfy enough.
I did add 3 electric fans to the back side of the condenser. 5 total, so that could be helping.
If there was a leak on the gauge set you would be able to feel it being cold due to the pressure drop and if it was humid it would probably have condensation where it was leaking. Your first picture shows condensation at the low side. But for it to leak that much that it doesn't make any difference in pressures getting above 30 it should have frost wherever it was leaking.
My gauge set has teflon seals on the hoses and they are notorious for loosening. I much prefer rubber seals on the hoses.
Had installed in our suburban windshield two years ago and have nothing but good things to say about what a improvement it made. We do live in the desert and it genuinely makes a big difference for us. I'll find out the exact brand we bought prior. DWMYH.
Scott
30 psi on the cold side should have colder temp than 58 deg. the senders shut down the compressor for too low and too high to protect it. The Low side must not be working or you wouldn't have had the compressor come on without jumping it to start taking refrigerant @ -10 psi.
If you actually had -10 on low and 100 on the hi side with no compressor running the gauges are no good.If it were mine here's what I would do,buy or get a good set of gauges,get a 30 lb. can of 134a,get some Red Angel stop leak,beg borrow or steal a vacuum pump,check for leaks using the pump,this way you won't waste the 134a,if no leaks put the Red Angel in and charge
unit with the 30 lb. can.
The drier may cost 50 but you have to remove all freon and then recharge with new.
If they change compressor "The compressor has a sticker with a 2017 date and looks new." They should have also changed the dryer. Just common A/C maintenance process.
Drier does not look as old as the coach.
Best of luck. My dash A/C cools great, but the fan decides when it wants to give more than low speed on it's own. While sitting in the driveway after getting home yesterday, the fan would go from high to low for about 20 seconds, then back to high again and repeat the process. Unfortunately, the dash AC wiring is not in any of my schematics other than the mode selector switch.
ETA: My dash AC was supplied by SGM Company. I called them and they were able to provide a schematic for the dash AC wiring. They were quite helpful in pointing me in the right direction of what to look at. Not sure if yours was built by SGM or not, but if so, their number is 440-974-6706.
I think I've found my problem. I'm not sure the original poster has an SGM system like my '03 does so maybe this is a split and move for Michelle :) , but SGM sent me a wiring schematic for the system and suggested the first thing I check is for 12V at the blower switch. I just turned the key on and while set to high, I've got low only (the default for the system when the mode switch is set to ANY setting), and there is only 4.4V to the blower switch. Without 12V, medium and high speeds will not run.
Since my issue is intermittent, I'm going to trace back the power wire and see what the deal is. Worst case, I'll tap 12V from somewhere else so this all works. For anyone else with a SGM dash AC system, I've attached the schematic they provided.
They also told me that the 15 bridge rectifiers are only used as diodes, not as bridge rectifiers. They are easy to source and mount, which also explains why they only used the DC in/out posts and not the AC posts of the rectifiers. I now have 5 spares. LOL
Yes I think the dryer and the compressor were done at the same time.
I have no idea if this is an SGM system, your diagram looks more complicated than anything I've seen in my system.
I did hook the gauges back up tonight after it sat for a couple days to see what the pressures were. It appears the system balanced itself out at just over 100psi. I have no idea what that means, can anyone provide some insight into those readings? The one good thing I see is it is holding pressure. At least I didn't lose all my refrigerant right away!
I am not sue how accurate the thermometer I was using is. Maybe it's colder? I forgot to mention to get the compressor to start before I figured out the mis-wired relay I did use a jumper to get it going. I added a couple cans of 134 with the jumper, then figured out the bad wiring on the relay, fixed that, and then the compressor ran on it's own for the rest of the filling.
That was the reading it showed when I first hooked them up. That was with the engine running but the compressor not turning. Perhaps the gauges are crap. I would not be surprised. I am going to run it like this for this trip (hopefully I don't kill it with the limit switch unhooked :o ) If it isn't working well I will probably take you advice and start over. Vacuum down the system, start fresh.
EDIT: After some research I came to the conclusion I better get that pressure switch hooked back up. I don't want to damage my compressor.
Mine has a sticker on the main unit under the dash.
That is a normal reading with the compressor not running
Guy I bought my FT from had spent almost $4000 and gave up. Just not worth it
When driving in to the sun, I love my dash A/C, as I feel the windshield gives off heat like a fireplace. In 2017 when I purchased my 1997 U295 the AC the compressor was not working, and I took it to a local AC shop. For approx. $1750 they replaced the compressor, expansion valve, dryer receiver, evacuated and charged the system, It has worked great ever since.
The forum within 30 minutes helped the shop and I locate the dryer and the expansion valve location in the rv, as I waited in the shop. By phone a forum member helped us find the dash location for the expansion valve. Thank you to our irreplaceable forum. I then walked a block away to Auto Zone to buy tools I needed to pull the center section dash out for the tech to access. I believe he charged me four hours labor. The following week I was going from Oregon to southern California, where I knew I'd need the AC.
So to update I removed 8 Lbs of freon and installed expansion valve. The dryer I had ordered did not fit. Spent hours chasing it down and have gone back to what I now believe to be correct. Ordered another receiver dryer and have missed my August 2 return limit. Bummer. 33474 crosses to the RD 8214c
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This one has a extra charging port I didn't need and will not affect but also has a moisture indicator. Never have used before but I already like. It does have the correct thread size for the binary switch removed from the old dryer.
Scott
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Got and installed new receiver dryer evacuated and charged with little over 8 pounds of Freon. Pressures now at 20psi and 300psi at 100 degrees outside. Dash air at 48 deg. This was at 1200 rpm. Will operate this week and see how it does. On the road should get lower dash temps. Having a evacuation recycle Freon machine really helps keep the cost down and being able to service Freon by the pound both out and in really a big plus.
Scott
Well a year later and a new pressure switch hooked up everything is still running cold. Someone had wired the relay wrong for the AC circuit as well, not sure if I mentioned that in a previous post.
I love it when problems get solved.
I don't use my dash air very often but it works great. Same with the dash heat.