Front AC Causes Transfer Switch to Click

[6.7LMegaCab]

Hello All! Trying to get our rig ready to hit the roads soon and need to sort out the problem with the front AC.

Last year this is what was done:

Moved AC breakers so there is one on each leg, before, both units were on one side of the panel.

New PD52DCSD Transfer Switch

New PD9260C Converter Charger

New PD1210SR Inverter

4x US 2200 6-Volt Deep Cycle Batteries.

On order, shipping TODAY: 2x SoftStartRV units.

Problem:

Front AC attempts to start and causes the transfer switch to start clicking. I turned it off, started the main AC and it ran just fine. Waited a couple of minutes and started the front AC and it ran just fine for quite a while. It eventually tripped the breaker.

I check the 50+5 start/run capacitor this morning and it appears to be okay, although, the fan side was reading around 4.7uF. The HERM side measured just a little above 50uF. Could this still be failing?

Setting the thermostat to fan only (AC off) the fan has no problem running, so it seems the problem is only on the pump side.

Could this be a telltale sign of a failing unit, a failing cap, or perhaps a wiring issue?

 

[6.7LMegaCab]

Here's a pic of how the WFCO A/C Box is currently wired - just in case it may help with diagnosing the possible issue with the AC:

 

[Dahillbilly]

have you double checked that the breakers are on separate legs, after you moved the breaker from one side to the other? I would disconnect from all power & check continuity from each breaker to the main legs (incoming power).

 

[6.7LMegaCab]

Yes, I have confirmed that they are on separate legs.

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[Dahillbilly]

give Heartland customer service a call, have the last six #'s of your VIN ready

 

[carl.swoyer]

Just a shot in the dark, open the transfer switch and check all the connections for tightness. I found a couple lugs loose and one wire loose and moving.

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[6.7LMegaCab]

I'll get in there and check that out, make sure the lugs are tight.

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[wdk450]

The transfer switch is essentially a big relay that should be normally (shore power supplied) DE-ENERGIZED. When you activate your auxiliary power source (generator or maybe inverter) the relay coils should be energized and the relay contacts switch to supply power to the trailer electrical loads from the auxiliary power source.

If you are getting the relay chatter when operating from shore power, then somehow voltage is getting to the transfer relay coil to start to activate it. If the chatter is happening when you are running on auxiliary power, I would guess that the voltage at the transfer relay coil from the auxiliary power source is too low to keep the relay solidly switched.

I am wondering if somehow the relay is miswired to make the coil and relay activate on shore power (which might be low voltage, due to wiring/connections/load) which would cause the relay to drop out and chatter. This wiring setup would leave you with no power if the shore power is interrupted until you start up your auxiliary power source.

 

[6.7LMegaCab]

The transfer switch is essentially a big relay that should be normally (shore power supplied) DE-ENERGIZED. When you activate your auxiliary power source (generator or maybe inverter) the relay coils should be energized and the relay contacts switch to supply power to the trailer electrical loads from the auxiliary power source.

If you are getting the relay chatter when operating from shore power, then somehow voltage is getting to the transfer relay coil to start to activate it. If the chatter is happening when you are running on auxiliary power, I would guess that the voltage at the transfer relay coil from the auxiliary power source is too low to keep the relay solidly switched.

I am wondering if somehow the relay is miswired to make the coil and relay activate on shore power (which might be low voltage, due to wiring/connections/load) which would cause the relay to drop out and chatter. This wiring setup would leave you with no power if the shore power is interrupted until you start up your auxiliary power source.

This is interesting! I replaced the original transfer switch because it would chatter as well. Since the one I installed was basically the same as what I replaced, except it has a monitor, I wired it just how the old one came out.

Now you got me wondering if there original might have been installed incorrectly from the factory.

Everything seems to run fine otherwise whether on generator or shore power and the monitor shows whether it's on Shore or Generator power.

I haven't been out there yet to pull the basement walls down, as I've got quite a bit to do before our vacation starts next week (without the RV- that trip is a little later). I may move more circuits around to balance the load a little better.

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[danemayer]

The PD-52 transfer switch looks for voltage on L1 to activate the contactors. The contactors will break if L1 goes below 105V. So chattering could be caused by low voltage. Is your A/C unit causing this?

You might swap the A/C wires going to their respective breakers. If the front unit is on L1, swapping would put it on L2. If that stops the chattering, that's a good indication that it's causing a voltage drop.

 

[wdk450]

BTW:
Any time you have the cover off of the transfer (or power protection) relays, this is an opportunity to give those 6 hardworking 50 amp contacts some attention to prevent future problems. File the contact surfaces with a small Swiss file, and finish the job with an application of electrical contact cleaner/restorer (Caig DeOxIt Red can is my preferred choice).

 

[6.7LMegaCab]

Thanks all for the tips and info (including restoring contacts)! That makes sense with regards to the chattering. I'll take the portable ammeter displays that I purchased and hook them up to see what the voltage is doing when the AC is turned on. I noticed too that L2 might have less loads on it...if I move the fridge over to L2, that might help when hooked up to 50A service (as it is right now-I typically fire up the Fridge when my sister and fam visits), so I'll just have to run propane if I end up at a park with only 30A service.

Caught a cold a few days ago, so I'm a bit behind on everything now. On the up and up now, so I should be able to start plugging away at it this weekend.

 

[6.7LMegaCab]

Update on this. I soon as I was on the up and up from a cold, my wife reminded me of our vacation (no RV) and the things I needed to get fixed so we can leave the chickens unattended. That took up my time up until we left Tuesday before Memorial Weekend. We got back yesterday and I went out today to install the SoftStartRV units. I have not pulled the electric panel cover or the basement wall down to inspect wiring. That is still on my to do list. However, the SoftStart was installed on the front AC first. That unit started up and ran with zero issues, blowing nice cold air for 30 minutes (approx 80 degrees weather). The unit never shut off, didn't vibrate, and the transfer switch didn't chatter at all.

So, I Installed the second SoftStart on the main unit, started it up and fired up the front AC and let them both run for another 30 minutes. Went back out, front AC shut off per thermostat settings and fired right back up when I lowered the temp some more.

So I'd say those units are working just fine now.

One thing I did notice was the front AC capacitor was probably replaced as it was round and the main AC cap was the more oval type and the cover had its lower side tabs pushed in, making it a pain in the rear to remove. I didn't look at the main unit cap to see if they were at least both the same size, which if the front was undersized, may have contributed to the hard starts... but that's just a theory.

The gen is due for its 400 hour service, so when I get back out there to do that, I'll work on checking the wiring as well.

 

[6.7LMegaCab]

Hello again!

Figured I'd post an update to all of this. I was able to get the basement wall down to access the transfer switch. A few lugs were ever so slightly loose, so I tightened them down even more (maybe less than a 1/4 turn out of them), but the problems persisted, just not as frequent after installing the SoftStart. One of the legs on the transfer switch kept disconnecting and while trying to reconnect, would just chatter until it lost connection altogether unless you were there to catch it and manually pressed the leg down. This would happen when either or both AC's were running, but not all the time. We could go a few hours or sometimes all day before it would disconnect. Sometimes 30 minutes and another reset. When resetting the main breaker to the RV, if the switch didn't engage all the way, it would smoke slightly. This is probably why the cover was quite hot to the touch.

I finally called Progressive Dynamics today. Unfortunately, they no longer offer the PD52DCSD (surge protection with display). Quite unfortunate as I had to cut a hole in the control cabinet for that display. They offered to send $100 to put towards a new surge protector and are sending out a replacement PD52.

It's been a while since I've talked to anyone up there, but either the one I talked to was having a bad day, or that's just the way it is. I definitely should not have had to poke and prod about my displeasure to give up a more expensive surge-protected device in exchange for a standard PD52. The PD52 is what came with the rig from the manufacturer, so at least it lasted 6 years.

Is the quality is starting to take a dive at PD? The current unit was replaced right after I bought it as there was a piece of the switch that arrived broke. Functionally it seemed okay, so I asked PD support about it and they opted to send a replacement.

Is there something better out there? Various websites that offer reviews of transfer switches seem all over the place, so I figured I'd ask here for a bit of input. I liked the fact they are (were?) made in the US. Any other manufacturers out there that make transfer switches that are popular among the Heartland Owners crowd?