A/C locking up in 1984 class c

[PlatinumSky]

I recently inherited a 1984 Kingston Midas camper, My great-grandparents were the previous owners and they take such good care of everything that the majority of the vehicle is effectively brand new. A couple of other relatives were taking care of it, and didn't have the time to perfectly care for the vehicle so I've been spending my time getting everything back and working order since it has such sentimental value to me. Fixed a bad fridge heating element, repair the water heater ignition, repaired the generator, etc. The only issue that I have now is that the air conditioner appears to run for a short period of time, it does pump out cold air, then within a few minutes, usually less than 10, the compressor locks up and then within seconds the circuit breaker trips. The fan is still running when the compressor locks up and there isn't any change in sound right up until the moment that it locks up or turns off. The odd thing is that when I take off the cover on top of the RV and hook up my AC manifold, It runs at the standard pressures for r22 refrigerant, comes down to about 60 PSI on the suction port, then equalizes about 85 psi. The part that's making it so hard to diagnose is that anytime I take off the cover and run the air conditioner, it just keeps running it doesn't stop, then as soon as I put the cover back on and try running it again it locks up and trips the breaker. Since the problem only happens when the unit is fully assembled I have no idea how I'm supposed to diagnose this issue. It blows nice cold air, even though there's a couple of dings here and there from bugs on the condenser it has plenty of air flow, The filters on the inside have been cleaned and have plenty of air flow as well, and the pressures I'm reading with my manifold seemed to match up with what everybody else seems to agree to be standard operating pressures for r22 AC systems. Forgive me if this is the wrong form to post in and I will immediately move it, in the meantime here's a picture of the manifold gauge hooked up to the unit, https://photos.app.goo.gl/1VUzC4gBb7TPGF8e6

And another picture with the name plate for the AC unit. https://photos.app.goo.gl/VCD6eMwaaemyo8AK8


If any of this isn't allowed in the forums I apologize and I'll remove immediately, this camper just has a lot of sentimental value because it's been around ever since my parents were kids, and I still hear stories about how my mom was chasing after my great grandparents in the camper when she was a kid.

[CavemanCharlie]

PlatinumSky wrote:

dedmiston wrote:

PlatinumSky wrote:
My buddy let me borrow his multimeter, it's holding a pretty stead 114.4 at the compressor. Oddly enough, hasn't tripped again even with the cover on and it's been running since I posted yesterday.

Another RV.NET success story. You're welcome. :B

Victory dance time, found the problems and it came in three flavors. 1) To begin with the first place I had it plugged in was by the shed at a relatives house, turns out their wiring is old from the 60's and someone just mounted a 30 amp outlet to the regular 15 amp wiring, was causing lots of voltage drop and luckily didn't start a fire. 2) turns out the generator also had a bad brush, and was making enough power for the fridge and phone chargers it wasn't quite reaching above 95v. And 3) the connection to common on the compressor went to another terminal under the shroud (? Not sure of terminology, the sheet metal enclosure underneath the outermost cover on top). This terminal was caked with a bright green powder I instantly recognized as heavily oxidized copper and practically fell off the spade connector when I touched it, I can only assume the cover was shifting the wires just enough to cause an intermittent connection at this point. In the meantime while it's working now I have it plugged directly into a higher amp outlet that was properly installed directly on the house, The new terminal I soldered in place is preventing any intermittent connection issues, and I had a brush that I borrowed from an old jet alternator a buddy got surplus that fits where the old one went after sanding the graphite to size. Still planning on eventually upgrading but happy it's at least working now. Thanks for all the help and suggestions everyone, only discovered the intermittent connection problem and I bumped the wires while checking the common terminal with the multimeter.

Congratulations ! You sound like the perfect person to inherit this old girl. You have the knowledge, patients, and time to keep it working. Please stick around on this board, help other people, and post about your adventures.

[mdcamping]

^^^ :C :C

[PlatinumSky]

dedmiston wrote:

PlatinumSky wrote:
My buddy let me borrow his multimeter, it's holding a pretty stead 114.4 at the compressor. Oddly enough, hasn't tripped again even with the cover on and it's been running since I posted yesterday.

Another RV.NET success story. You're welcome. :B

Victory dance time, found the problems and it came in three flavors. 1) To begin with the first place I had it plugged in was by the shed at a relatives house, turns out their wiring is old from the 60's and someone just mounted a 30 amp outlet to the regular 15 amp wiring, was causing lots of voltage drop and luckily didn't start a fire. 2) turns out the generator also had a bad brush, and was making enough power for the fridge and phone chargers it wasn't quite reaching above 95v. And 3) the connection to common on the compressor went to another terminal under the shroud (? Not sure of terminology, the sheet metal enclosure underneath the outermost cover on top). This terminal was caked with a bright green powder I instantly recognized as heavily oxidized copper and practically fell off the spade connector when I touched it, I can only assume the cover was shifting the wires just enough to cause an intermittent connection at this point. In the meantime while it's working now I have it plugged directly into a higher amp outlet that was properly installed directly on the house, The new terminal I soldered in place is preventing any intermittent connection issues, and I had a brush that I borrowed from an old jet alternator a buddy got surplus that fits where the old one went after sanding the graphite to size. Still planning on eventually upgrading but happy it's at least working now. Thanks for all the help and suggestions everyone, only discovered the intermittent connection problem and I bumped the wires while checking the common terminal with the multimeter.

[dedmiston]

PlatinumSky wrote:
My buddy let me borrow his multimeter, it's holding a pretty stead 114.4 at the compressor. Oddly enough, hasn't tripped again even with the cover on and it's been running since I posted yesterday.

Another RV.NET success story. You're welcome. :B

[PlatinumSky]

My buddy let me borrow his multimeter, it's holding a pretty stead 114.4 at the compressor. Oddly enough, hasn't tripped again even with the cover on and it's been running since I posted yesterday.

[PlatinumSky]

mdcamping wrote:

#1 Has the A/C been serviced/charged before? "over charging" is a common problem which drives up head pressure & amps, also increases the risk of flooding the compressor. Taking the cover off & getting the extra air might just be enough to keep the compressor running under FLA or trip point of the overload. Check running amps see if your running above FLA. (Full Load Amps)

#2 because of age of the compressor it could be just tight, and again taking the cover off just might be enough to keep the compressor running under FLA or the trip point of the overloads. Under those circumstances would be best to scrap the compressor/unit

Good luck
Mike

Thanks, my GG Parents were the only previous owners besides another relative taking care of it for a couple years, no service work has been done on the ac, only work done was to replace a recalled control board on the fridge. The pressures seem to match up with what's commonly accepted for r22 AC (85psi low side).

Honestly I'm planning on changing it when I can afford it because it barely keeps it cool, just not something I can afford yet so trying to find an alternative until funds are available. I've worked on refrigeration systems before, swapping compressors, tuning cap tubes, and tuning systems before, just not sure where to start with this once since I can't find any specs on the compressor that I could use as a stop gap until I can get a better unit.

[PlatinumSky]

Gdetrailer wrote:
The A/C is from 1984?

Time to replace it.

RV A/C units are factory sealed with zero refrigerant ports and were never intended to be serviced.

The fact you have ports, means someone has added ports and has been worked on before.

Not worth dropping money on a new compressor in an A/C unit this old which may have potential small leaks in the refrigerant lines (remember, someone did add ports for a reason).

Your not going to change "sentimental value" of the RV by replacing the A/C unit.

The service manual shows the low side service port I've been using so it did come built in to the unit. My great grandparents, the original owners, never had anyone work on the AC, and my GGPa doesn't do refrigerant work and they said nobody else did a recharge on the system, since there aren't any other owners besides them and with how carefully they take care of their tools and vehicles I feel pretty confident in this claim. Besides a recall for the fridge control board, they haven't done any major work besides preventative maintenance and changing a couple engine parts.

Since the unit is still at pressure without having been worked on, that was the reason I was considering replacing the compressor, I have easy access to low cost compressors from a friend in the industry but I don't know the specs for the compressor, googling the model number trust comes up with the service manual for the whole unit which is where I checked that the service port really was factory installed (low side only, no high side port).

I agree about changing the whole unit, honestly it has trouble keeping up with the summer heat, buy replacing the compressor would be much more within my budget than changing the whole unit, otherwise I would gladly do so.

[PlatinumSky]

hypoxia wrote:
Is there any chance the cover is blocking air flow through the condenser? That would cause those symptoms.

Don't have a meter to measure the actual air flow, but just feeling with my hand it seems like the air flow is about the same either way.

[mdcamping]

PlatinumSky wrote:
I recently inherited a 1984 Kingston Midas camper, My great-grandparents were the previous owners and they take such good care of everything that the majority of the vehicle is effectively brand new. A couple of other relatives were taking care of it, and didn't have the time to perfectly care for the vehicle so I've been spending my time getting everything back and working order since it has such sentimental value to me. Fixed a bad fridge heating element, repair the water heater ignition, repaired the generator, etc. The only issue that I have now is that the air conditioner appears to run for a short period of time, it does pump out cold air, then within a few minutes, usually less than 10, the compressor locks up and then within seconds the circuit breaker trips. The fan is still running when the compressor locks up and there isn't any change in sound right up until the moment that it locks up or turns off. The odd thing is that when I take off the cover on top of the RV and hook up my AC manifold, It runs at the standard pressures for r22 refrigerant, comes down to about 60 PSI on the suction port, then equalizes about 85 psi. The part that's making it so hard to diagnose is that anytime I take off the cover and run the air conditioner, it just keeps running it doesn't stop, then as soon as I put the cover back on and try running it again it locks up and trips the breaker. Since the problem only happens when the unit is fully assembled I have no idea how I'm supposed to diagnose this issue. It blows nice cold air, even though there's a couple of dings here and there from bugs on the condenser it has plenty of air flow, The filters on the inside have been cleaned and have plenty of air flow as well, and the pressures I'm reading with my manifold seemed to match up with what everybody else seems to agree to be standard operating pressures for r22 AC systems. Forgive me if this is the wrong form to post in and I will immediately move it, in the meantime here's a picture of the manifold gauge hooked up to the unit, https://photos.app.goo.gl/1VUzC4gBb7TPGF8e6

And another picture with the name plate for the AC unit. https://photos.app.goo.gl/VCD6eMwaaemyo8AK8


If any of this isn't allowed in the forums I apologize and I'll remove immediately, this camper just has a lot of sentimental value because it's been around ever since my parents were kids, and I still hear stories about how my mom was chasing after my great grandparents in the camper when she was a kid.

#1 Has the A/C been serviced/charged before? "over charging" is a common problem which drives up head pressure & amps, also increases the risk of flooding the compressor. Taking the cover off & getting the extra air might just be enough to keep the compressor running under FLA or trip point of the overload. Check running amps see if your running above FLA. (Full Load Amps)

#2 because of age of the compressor it could be just tight, and again taking the cover off just might be enough to keep the compressor running under FLA or the trip point of the overloads. Under those circumstances would be best to scrap the compressor/unit

Good luck
Mike

[hypoxia]

Is there any chance the cover is blocking air flow through the condenser? That would cause those symptoms.

[Gdetrailer]

The A/C is from 1984?

Time to replace it.

RV A/C units are factory sealed with zero refrigerant ports and were never intended to be serviced.

The fact you have ports, means someone has added ports and has been worked on before.

Not worth dropping money on a new compressor in an A/C unit this old which may have potential small leaks in the refrigerant lines (remember, someone did add ports for a reason).

Your not going to change "sentimental value" of the RV by replacing the A/C unit.

[PlatinumSky]

katysdad wrote:
check your voltage at compressor. low voltage will overheat a compressor and cause the thermal overload in the compressor to trip.

Once I get my new probes in the mail I'll check the voltage, the grounding probe on my multimeter broke so I'm waiting for a new one. I might be able to borrow a friend's who does some crazy stuff with radio transmitters.

[PlatinumSky]

agwill wrote:
Those older AC units have oil ports on motor that need to be oiled on both sides. Take cover off and check for little oil caps on either side of the motor.

I found and oiled those on the blower motor, it spins really smooth by hand when the cover is off and it keeps spinning even with the compressor stopped so I didn't think it was part of the problem but I'll take a closer look at it as well.

[PlatinumSky]

okhmbldr wrote:
How are you powering the A/C? Generator? House Power? If you're using an extension cord for power you might be using one that's a little to small. Extra heat will build up and shut off the compressor, then trip fuses. Heavy duty cords are best. And good luck with this old gal.

I've ran it from both a 30 amp RV outlet as well as the built in Onan 4000 series generator, same results both times. The ground probe on my multimeter broke so I don't have a way to check the voltage right now but I'll do so once my new probes come in the mail.