Dash AC kaput!

[siggyd]

So,if the compressor clutch is not pulling IN,can you take an Ohm reading on the clutch. With the wire dis-connected,check between the wire and a good ground. You should get a low ohm reading. ( 20 ohm or less,I'm guessing)
But it should not be zero.
Siggy

[Roscott]

Well, now I've gone and done it. I wasn't able to get a reading per your instructions Siggy. But, I can't guarantee I used the meter correctly or that it was working properly. I was using some fancy digital one I really haven't used in years and not sure I had it set correctly. Anyway, to check that I went to the front and couldn't get any ohm readings there and when I tried to double check voltage, I didn't get a reading. Checked voltage with my analog meter and it was fine. So, I think there may be an issue with the digital meter. BUT, before I went to check ohms with the analog, I used the digital to check voltage on the high pressure (I have no idea why I did that ) and shorted something or blew a fuse somewhere as the system just shut down and now when I turn AC on, nothing happens. Checked fuse under dash and it was good. Not sure if there is another somewhere?

[Roscott]

Update: not fixed, however, I did find the fuses I blew when I shorted 12v to ground from the high pressure switch. In the fuse cabinet in the front end with the generator, bottom console, there were 2 fuses. 1 for blower and 1 for AC...I got both. Need to run to the parts store and buy some micro fuses.

I still need to buy a high pressure switch as mine is leaking. There are no markings on it and I have no idea what to order. Auto parts stores had no idea when I took it to them. Can I just purchase one that is similar that will fit, or do these things have preset pressure readings dependent on your system that I need to be aware of? I'll also check to see if the Evans documentation has anything for a replacement part.

[bluepill]

There are a few different styles of pressure switch. Main difference is thread size and electric connection. Use google to find web sites with illustrations and specs. Lots of sources to buy. Don't forget Amazon, especially if you have prime.

Make sure that you know if you are dealing with the high pressure or low pressure switch, or a combination that monitors for either high or low.

Good place to start:

http://www.4s.com/en/

[siggyd]

For the LOW presure switch,you need to go on the EvansTempcon website.
And remember,when measuring OMS, all power must be OFF. (or you will damage your meter).
The OHM reading for the compressor clutch should be between
2 to 5 Ohms.
Siggy

[38Chevy454]

The pressure switch is there to be normally closed (conduct between the two terminals) when the pressure is within the normal range. If too low, then switch is open, or too high of pressure it is open, both to save the A/C components. The basic circuit is when you put A/C switched to on at the dash, 12v is run to one side of the switch. Then if pressures are good it conducts the 12v to the other terminal. Nowhere does the switch go to ground, as you found out with blown fuse. The wire at your compressor is what is connected to the side of the switch that is closed, and supplies 12v to the electromagnetic clutch which turns the compressor. When no A/C the compressor pulley freewheels and the center is not supposed to rotate. Hope that quick explanation helps.

Arbitrarily adding refrigerant may fix the problem, if it was low on refrigerant. You really need both low and high pressure gages and the readings to accurately charge. If in doubt undercharge is better, especially with R134a. Without full pressure readings it is hard to diagnose the exact problem.

If the pressure switch is leaking, when you unscrew it there should be a schrader valve under it to seal the system off and therefore saving the system form leaking all the refrigerant and much of the oil out. As long as you get a switch that has same thread and same basic pressure points it should work. Check for any mfr P/N on the switch once it is removed.

[Roscott]

Update to the update: Thank you all for your input it has been very valuable. I replaced the fuses and, as expected, power returned to the unit. I verified I had 12v where needed. I then jumped the pressure switch, briefly, and the clutch engaged.

For grins, I cleaned up the switch and reinstalled it. Wanted to see if the system would work and if it still leaked (maybe the high pressure was causing the leak?). Again, success. Clutch kicked in, I heard the freon cycle through the system and the switch did not leak. I let it run for several minutes. I had released some refrigerant from the high pressure line earlier just to make sure there wasn't a clog (at least that was my thinking). I put the gauge back on the low pressure side and it showed low so I added some freon back in. I did not have enough to get it in the green, but it did get cooler. I'll need to get more 134 and add it. I will also try to get some proper gauges and check the high pressure.

I have no idea what 'fixed' it. I think it may have been a combination of things. Too much refrigerant causing high pressure and the valve to stay open and perhaps the AC fuse that I found was blown. Anyway, I'll measure the pressures again. Add refrigerant as needed and keep an eye on it.

I'll post back to this thread if I run into any other hiccups while I try to wrap this one up.

Had it not been for this forum, again, I would not have been able to do the troubleshooting I was able to do. Thank you all again, this place is worth its weight in gold!

[DD788Snipe]

My money is on corrosion on the connectors and blown fuse. Always go for the simple stuff first.

["007"]

For future reference these Evans links SYSTEMS --- Trouble Shooting Guide should help you found in QT's # 3.
This thread has to do with the EVANS Control not installed correctly.

EVANS SERVICE AND PARTS LINKS

[Roscott]

Originally Posted by 007";3148609]For future reference these Evans links SYSTEMS --- PARTS should help you found in [B][URL="http://www.irv2.com/forums/f103/newmar-quick-tips-and-easy-mods-3-a-113631.html

QT's # 3.[/URL][/B]

Thanks 007, I'm going to need those. It turns out that once I got the system back up to pressure, the switch started leaking again. Also, I could not get the temp coming out of the vents below 70 degrees. I cut off the flow from the heater hose, but that didn't help. In fact, after a few minutes something in the rear blew and refrigerant went everywhere. I was hoping there was some type of pressure relief valve back there and that I didn't burst a hose (I know, wishful thinking). But, I removed the clamp from the hose, checked the freon level (it was low again, of course) and added what I had left. It didn't get me all the way to where I needed to be, but there was also no leak in the back as i suspected there should be.

Anyway, need to order a pressure switch and I also have a temp sensor I'll replace at the same time. So, I'm stuck until I get the new part. Will update again once that happens.

[cvbdsl]

I had no AC and I gave up on mine and went to the pros - leaking compression fitting, expansion valve sticking and new receiver dryer.

Unfortunately, parts were around $90, refrigerant $136 (for 6.5 units) plus labor at $80 per hour. Invoice did not break down time spent on the AC vice other items, but I estimate it cost around $700 (including 13% tax)to fix.
(all in CAD so subtract around 28% for USD)

Great if you can fix all the issues yourself - go for it!

So far around $4500 spent on the MH this year in maintenance, but some things you gotta do.

Chris

[Roscott]

Chris, you make a good point and I'm well aware the option of going to the pros is waiting in the wings. I just like trying some things myself first. Worst case, I make it worse (this may be one of those times ), best case, I fix it. Either way, it's a learning opportunity.

["007"]

You need to realize the the hoses travel through your chassis rails and its been necessary for some members to have to replace both hoses for heating and AC, age of coach and environment will decide replacement time.
The pressure must be going high for system.

[Roscott]

Originally Posted by "007"

You need to realize the the hoses travel through your chassis rails and its been necessary for some members to have to replace both hoses for heating and AC, age of coach and environment will decide replacement time.

Yep, thought of that, broke out in a cold sweat, then went back to crossing my fingers!