oneway

Update as promised: thanks to all here who helped me properly diagnose the issue. I got thru the warm Yuma winter and the RV is going to the shop this morning for a new A/C. they will replace the unit for 1 hr labor, and I deranged my shoulder somehow and am in physical therapy so no choice there and cheap enough! next camping trip is in August so I'll be happy to have the 2nd A/C.

Tehachapi. Should be back in about 3 weeks or so.

Thanks for all the help. My A/C's are ducted. if I decide to tackle the job: I have a friend with a decking around his house and a walkout basement. We can drive the Motorhome next to his house and put gravity on our side. I think I'm gonna use the one A/C here until I get home to the cool mountains of California.

Yes, the test results show a bad compressor and so I see no need to smoke test my new start cap. I have had this thought: I could go to the front (good) A/C and put in the new start cap there, then move the used but good start cap from that A/C and smoke test it in the rear (bad) A/C. I wouldn't feel bad if that went up in smoke. the only thing keeping me from doing that is I don't want to take a chance on losing the good A/C for some reason until I can get home in about 3 weeks.

Well, first let me say Kaypsmith that you have been extraordinarily patient with me and I owe you particularly a beverage of your choice for helping me understand. my ole brain is trying to come along for the ride and I think I've finally got it with that last explanation...maybe. anyway, NO I didn't say...or mean to say that I FOUND red-black was =6 what I tried to say was that I thought I was supposed to FIND 6, but only FOUND 4 in the red to black wire measurement. That's why I provided the pictures of the meter readings. and earlier before your last explanation while my head was spinning a little faster I thought maybe you were trying to tell me I was looking for this formula: 4+1=5 Now I believe I understand that the sum of each of the wires (red + black) , each measured separately to common (white).. should equal the measuring of red to black.... therefore if red to white = 5, and black to white = 1, the red to black should equal 6 Yet I only found red to black =4. so I can go up again to make sure the red or black doesn't have a dead short to ground now, but with my findings isn't that futile? I hope anyone following this thread that doesn't have any electrical background is getting as much out of this as I am. i sincerely appreciate it.

So after more research with online videos and other sources here is where I think I am: 1.continuity test is good 2. In the Ohm check: Common to start and common to run should equal start to run, and start to run should be the highest number.( in my case the red-black) This is where I believe my test fails. agree?

I haven't put in the hard start kit yet to test it. I can do it in the morning but there is no sense in doing it just to watch it go up in smoke so more questions then. 1. Yes, I have continuity between all points. Red-white, black-white, and red -black.....I thought that was a BAD thing. Am I wrong? 2. I thought since white is common(which it shows on the schematic), then here is what I understood: If red-white =5 And white-black =1 then I was supposed to find that red-black would read 6. Yes?? I have to admit my head is spinning a bit as this is my first attempt to understand all this.

I am careful. I make sure all power is off. I wear rubber gloves. I try to discharge the capacitor I'm taking out, and I use insulated pliers. so test the new start cap with the intact PTCR is your recommendation?

Here is the schematic on the back of the AC. So........input? time for an A/C? Or smoke test the start cap with the PTCR???

So... continuity between all points. but white-red =5, white-black=1 the sum should be red-black =6..... correct???? And I've got basically 4.0 maybe 4.1. i disconnected the wires so I was reading only the compressor and no other capacitors online. now I just re-read the "if the resistance of 2 equals the highest ohm reading"..... so if I apply that....then: red-black=4 white-black =1 white-red=5 and that adds up.

White-red=5 White-bLack=1 Red-bLack = 4.1 W-r= cont W-b=cont R-b=cont here is what I found on the roof with my meter...

OK. this is just a thankyou picture for all the help. The story continues next....

Thanks for all the insight! there is a schematic inside the door that houses the capicitors. I will do a test and see what I find. May not be until Sunday. Tomorrrow I'm going to watch the Blue Angels fly in El Centro! I'll post my findings here as well so that others can learn from my experience. I'm learning as I go. Never done this before. My MANY THANKS to everyone who has helped me this far.

Ok. So the compressor has 3 wires: red, black, white. I understand white is supposed to be common. so so do I just test: red-black, black-white, white-red....and I'm done? And I'm not looking for continuity (the tone)? But measuring resistance and looking for 2 numbers to add up to the 3rd? I might as well try this part out and see what I get. I've lost all faith in the techs here. I'm close to putting that 2ndstart cap on with the PTC and just trying it. It would be a $37 experiment. No big deal at this point.

And now to the Hair Dryer Test results: I put the coach on generator power and let it stabilize. A few minutes later the front A/C was put online and was stabilized for about 5 minutes. I added the hair dryer on low setting. Next hair dryer on high setting. Then I added in the electric water heater. Each time a load was added there was a slightly (if at all) perceptible sound difference in the genset. It ran everything without bogging down at all. I guess all roads lead to the rear A/C again? With all loads online the line voltage monitor shows wavering and even dipped slightly below the green arc momentarily.(top picture) With only the front A/C on the line voltage monitor shows a slight wavering and remained within the green arc.(bottom picture). now...... input?

"If the compressor isn't running there should be 3 leads common, run and start coming directly from the compressor. Check between the leads for continuity. Common to run, run to start, and start to common. If the resistance of 2 equals the total of the highest ohm reading between the leads the compressor is good and the problem is something other than the compressor such as low freon overheating it. If you get continuity or 0 ohm across any of the lead sets than the compressors internal windings are bad and can only bring fixed by a compressor replacement." I found the above quote on the web while searching for how to test A/C compressor resistance. This sounds like what the tech was saying when he said the resistance should "double". I've got a cheap VM. (Radio shack). I can test continuity and it gives me a tone. Still waiting to see if anyone can explain the difference between those 2 capacitors.

When I went to replace the capacitor here is what I did: I took the original capacitor in to the RV supply place and they matched up the numbers. They gave me a new capacitor that looks like the top picture with the (resistor?? I guess) between the terminals you see there. The guy thought maybe it was an updated version. That one I installed and it blew. Now....I went back and the second time they gave me a capacitor that looks like the bottom one. Is that the PTR/PTC there on the top? The red wire attaches to it, then it connects to a terminal on the capacitor. After looking at the initial blown capacitors pieces it is clear to me now that the bottom one would have been what i had originally. i have that hard start kit ready to install. But again, I don't want to just smoke test a part. The tech said the compressor did not have a dead short. He said something about the resistance was supposed to double between 2 wires that he tested and it wasn't double. I don't have a clue what that means. anyway....any input on the difference between the capacitors?

I'm going to do the hair dryer test today before going any further. And I'll show a few capacitor pictures here as well. maybe someone can tell me if I was given the correct capacitor from the RV shop. just got a call late yesterday as well from Tech #3. A new A/C is $708 and about $200 to install. (Coleman Mach III).

My wife has a hair dryer here. 1875 watts. If I understand you correctly then: 1875 W / 120 = 15.625 amps. so I can try to run that with the front A/C. Or is that too much amperage to add?

I don't have a heater with me. I do have one at home, not sure the watts. is there a combination I can try here with 1 A/C and say the electric H20 element along with Microwave?

While it's interesting to see where this hads led, there really hasn't been any straying from trying to figure out why the Genset bogs down when trying to start a second A/C. I've been led all over by 3 techs, that's for sure. I've come back to this forum each time to recap and see if any of them are on the right track. I'm not a technician so I need advice. tech # 1 says it bogs down because the gen set needs a complete removal and rebuild. tech # 2 says it bogs down because because the gen set needs a new carb. after advice on this forum I checked and found the rear A/C wasn't starting on shore power as well (neither of the first 2 techs figured this out). Plus I found a blown start Cap on the rear air. (Techs didn't find that either). I replaced the start cap (with what the parts guy gave me when I took the old one in), and it blew the new start cap that may not have been the correct one. So I called tech # 3 who: checked the resistance on the rear A/C and declared it dead. (BTW, I had to show tech # 3 where the capacitors were on the A/C unit. He was clearly unfamiliar.) now..... im still trying to figure out why the gen set bogs down when I try to start the second A/C. but I have to follow where the road leads. so far it has led here. I have little faith in the techs at this point.

Here's the latest: Had tech # 3 here today. I went up on the roof with him and watched as he heckled the resistance of the compressor. He unplugged the red, white, and black wires. He checked the resistance between 2 of them ( don't recall which color), then he says the resistance between the other 2 should be double what the previous reading was.....which it was NOT. Then he declared my A/C bad and went off to find out how much a replacement unit is. Will find out in the morning. Anybody know the testing procedure for the compressor? Did he do it right?

I have the correct part in hand. I'm just gonna let a tech do it since he can appropriately check to see if there are other problems as well. the parts guy gave me a replacement capacitor without the PTR/PTC. (Whichever it is.) on the initial replacement. I just don't want to blow this one as well. and yes, it's a Coleman Mach III and by replacing the set you mean on the front A/C as well? Or a set meaning all the capacitors in the bad A/C?

Here you can see what I found initially. Clearly the plates have burnt and separated and I only found some plastic pieces. Now I know that these plates are inside that PTR. remeber, the parts guy just sold me a replacement capacitor with a resistor soldered between the 2 spades on the capacitor. It did not have the PTR on it. stay tuned

Update to the update, update: i went to the RV supply store and talked to a different guy. He showed me this exact part. Bear with me because this is a learning experience for me..... the capacitor they previously sold me did not have the PTR shown here. Now I understand as I put 2 and 2 together what it was that I observed when I described the plates I found burnt. They were inside the plastic housing shown here attached to the red wire. so I now have purchased this exact start kit and have a technician scheduled to come check out the unit to prevent me from smoke testing another $35 part. stay tuned. Tuesday is Tech day. my thanks to Ziggyh for a spot on explanation with photos. I'm gonna try to attach some photos as well so you can see what it looks like from my end.