Community Forums

gbonner · 05-11-2011, 08:18 PM

The Problem:

I have a 2008 Holiday Rambler Endeavour with the SCS Frigette Dash A/C. When we are on the road and turn the dash air unit on we notice the air starts out cool but after a period of time gets hotter. At a gas stop, I decided to check the fuses and the "A/C Clutch Fuse" (20A) is usually blown. I've since replaced the fuse 3-times.

What I've done:

I checked the R-134A freon level with my gage set. The pressures with the A/C on MAX - compressor verified running, condensor fan spinning, low side was 35 at 70 deg F and high side 130. The high side seemed low, so for comparison I checked my 2004 Jeep that has good cold air conditioning and the Jeep low side was 45 and high side 200. Assuming I needed to add freon, I charged with a new can but only got minimal pressure increase. I checked the temp and it was about 20 deg below outside air. So idling, everything seemed to work.

I also checked all the fittings for leaks and found nothing. During gage testing I noticed that as the compressor cycled on and off (condensor fan ran at the same time) the low side pressure would immediately drop to 20-25, but would recover to 35-40 when the compressor kicked in. High side pressure was still only at 130.

Things I'm considering:

1) I saw a post on this blog where the compressor fan may scrape the condensor housing when running down the road, creating resistance, possibly causing the A/C Clutch fuse to blow? This might be the problem as I tested the A/C with the pressure gages for 30 mins while idling in the storage lot and the fuse didn't blow. The cold air output was good, but the gage showed the high side was lower than normal 150+ so I am still not sure it will work on the road.
2) Since the temp checked fine while idling, the other problem I saw on this blog noted the heater valve may be stuck, blending hot air with the cold air. This might cause the condensor to freeze up from over work and blow the A/C Clutch fuse? I am going to install a manual shut off valve this week to eliminate this problem.
3) Additionally, I may have a pressure switch, temperature sensor or expansion valve problem.

That is about all I have, and would appreciate insight from those who have had similar problems.

Mike Canter · 05-11-2011, 09:26 PM

The compressor clutch doesn't change the amount of amps drawn if the load on the compressor changes. It is a fixed current draw through the coils for the clutch magnets. If the compressor is not turning and the clutch has power then the current draw is the same as if it was turning. If the compressor goes bad and locks up then the clutch hopefully will slip but the current draw will be the same. Providing there is nothing else on that clutch fuse circuit then I would say that you have a AC compressor clutch that is possible shorting out after it heats up. They are not that hard to change. You can do it with the compressor still mounted without letting out any R134.

In case you didn't know SCS Friggete is shutdown. The phone rings and voicemail is there but nobody home. All you need is the make and model of the compressor to get a clutch.

The other option is to put in a 25 amp fuse and see what happens or even a 30 amp fuse.

As far as the pressures you are only really interested in the low side pressure when adding R134a. Check the air temp going into the condensor with it in MAX and fan up high look it up on the temp/pressure charge for low side. Since the whole system takes 4 lbs of R134a then if it is low it may take several cans to bring the pressure up.

RVhauler · 05-11-2011, 11:48 PM

Rather than replace a higher amp fuse i would replace the fuse with a circuit breaker. (available at any auto parts store). However recommend that you check the power feed circuit for a bare spot shorting out the fuse. have seen a number of clutch pulleys that rubbed on the wire and shorted out

gbonner · 05-12-2011, 07:17 AM

Mike: Thanks for clarification on the clutch operation, I have a wiring diagram (found on this blog) and the condensor fan is the ONLY other thing on that 20A circuit, although the fuse is 'front ended' by a mini-relay.

So with that advice, I'll focus on the electronics and not worry about the freon charge once I check the ambiant temperture at the condensor as you have suggested - although should not cause the A/C Clutch fuse to blow. Funny thing on the freon charge is that it would not take the whole can and I administered it for 20-minutes while the clutch/condensor fan cycled on-off many times during that time. I assumed it was full, maybe too full? I know the low and high sides should tend to equalize when the A/C is turned off, the low side climbed when I turned it off, but it never got over 45 PSI, while the high side was still at 100+ (my test with my Jeep showed the two sides almost balancing). So I am wondering if I also have a valve or pressure switch problem (although not related to the A/C Clutch fuse problem)?

Yes, I knew SCS Frigette is gone but now supported by Victory Climate Systems - their website URL now redirects to Victory's and they have docs online but only show photos and model numbers of the units, compressors, switches, etc. If need parts, the website says to call with the part numbers. So once we get this isolated I should be able to get the parts.

RVHauler: Good ideas, I will trace the clutch positive wire and look for wear near the compressor. I'm going today to buy several sizes of fuse replacement relays.

Thanks again folks, I will keep you updated, the condensor fan resistance or positive A/C Clutch lead shorting seems like the most likely culprit, but let me know if you have anymore ideas. -Glenn

Mike Canter · 05-12-2011, 07:36 AM

It could be just no short but the power drawer of both the clutch and the fan is close too 20 amps. A 25 amp fuse should show you that. If it doesn't blow then everything may be OK. If it blows then you may have a more serious problem like a short. (This is Navy troubleshooting.....just keep increasing the size of the fuse until you see smoke)

As far as adding freon the only way that you can get all of it out of a can is to sit the can in a pan of hot water. Make sure the can stays upright so you don't get liquid.

Your Jeep is an orifice system but your MH uses a Block Expansion valve so there will be a difference on the pressures leveling out when the compressor shuts off. The orifice system in the Jeep will equalize real fast. The expansion system will not.

One of the big failure items in that condensor fan because of its location but you say it is working OK. Is it free spinning or hard to spin with no power?

That is great on Victory Climate Systems. Looking at the website I would say that it is the same company with a new name after a bankrupcy filing because they have the same address as the SCS/Frigette.

pwhittle · 05-12-2011, 07:46 AM

Be careful with the temperature if the water. A friend of mine, thinking more was better, used boiling water. The resultant explosion of the can left him with severe burns and extreme pain.

I typically use a bucket of room temperature water to soak away the cold on the can as the R134A releases from the can.

Patience is a good virtue in this activity.

Paul

Mike Canter · 05-12-2011, 07:49 AM

Good point. I should have specified because a lot of people read these posts. I use hot water right out of the faucet which for me is about 120*.

Lt46 · 05-12-2011, 07:52 AM

Don't hold your breath on Victory being helpful. I've been emailing them over the past week regarding parts availability for my coach and have been getting short answers I.E. "part not available".

Mike Canter · 05-12-2011, 08:49 AM

It will probably take a while to fully recover. lets hope so. Most of the actual AC parts are available from AC suppliers. The only thing that is really not is the ducting and plenums and things like that. Have you called them and asked who made the part you need and the part number?

gbonner · 05-12-2011, 07:53 PM

Thanks for the follow-up, I had to play golf (again) today, but will get over to the coach tomorrow and test the recommendations. -Glenn

gbonner · 05-16-2011, 01:24 PM

Just an update on my SCS Frigette Dash A/C problem: I figured out why the A/C unit wasn't taking the charge. I had a defective gage puncture valve that wouldn't let the freon out, hence none went in. Once I got a replacement from the Carquest Autoparts store, I was able to drain four 14oz cans into the lines before the high side and low side showed normal for the ambient temperature.

If that was the problem then maybe it is fixed unless there is a really big leak. I did replace the A/C Clutch/Fan fuse with a circuit breaker type of the same (20A) amperage. I checked the condensor fan and it rotates freely and am getting one really warm side and much cooler on the opposite side. The temperature drop inside the vent with the A/C on MAX and high fan speed is approximately 30 degrees. I could never get the fuse to blow while idling in the parking lot. We are leaving on a trip in one week and hope the problem is solved. I will update this thread once I test it on the road. Thanks again for the help.

Mike Canter · 05-16-2011, 01:28 PM

Well all is sounding really good. I hope all works OK. Those dash AC units are not the best. In real hot weather you can only get about a 20* differential out of them.

gbonner · 05-17-2011, 08:44 PM

Thanks Mike, I'll keep you updated, we travel the southwest and the heat only gets worse in the summer, so I'm adding a clear shower curtain just behind the driver's seat to help keep us cool when on the Recirc mode.

Mike Canter · 05-17-2011, 09:48 PM

That circuit breaker will be able to take fast acting increases in current draw without blowing like a fuse. Sooner or later the problem is going to get worse and start popping the breaker.