HELP! Front A/C quit working today

[Idoc57]

Murphy's Law at work!  We leave Monday morning with the Grandsons to go see the Ark and Creation Museum.  I turned the front A/C on this morning to cool the coach down (rear was off) and about mid-day we lost power for about 2 seconds (literally).  Off and right back on again.  Went by to check some things on the motorhome and noticed that the A/C was not running.  First checked the breaker in the bedroom, it was on.  The A/C's are both Carrier Low profile units that operate with remotes.  When I turn it on and switch modes I can hear the little relays closing, there is just no fan.  I switched the main capacitor and another small electrical device (picture below) from the rear air into the front air.  Didn't help at all.   Any suggestions would be helpful.  Thanks, guys.

Carey

[MyronTruex]

Did you take a voltmeter up there? You may not have 110 volts. The relays are likely run by 12 volts.

If you do not find 110 volts inside the AC unit you will have to go to your ac breaker panel and see if there is actually power coming out of the assigned breaker. And if it is there, move on through the load shedding relay board. 

If it is a load shedding issue you can temporarily bypass  that one control relay. 

Of course I'm typing away without knowing what rig you have but this might help. 

 

OK, 2006 Cayman it appears and it most likely has a load shedding device. 

Edited June 11, 2023 by myrontruex

[Idoc57]

41 minutes ago, myrontruex said:

Did you take a voltmeter up there? You may not have 110 volts. The relays are likely run by 12 volts.

If you do not find 110 volts inside the AC unit you will have to go to your ac breaker panel and see if there is actually power coming out of the assigned breaker. And if it is there, move on through the load shedding relay board. 

If it is a load shedding issue you can temporarily bypass  that one control relay. 

Of course I'm typing away without knowing what rig you have but this might help. 

 

OK, 2006 Cayman it appears and it most likely has a load shedding device. 

Thank you Myron for responding.  My plan for this morning was to do what you said and start at the breaker panel and then see if there was 115 volts at the unit itself.  What I had not even thought about is the Intellitec load shedding device.  If I have power at the A/C unit, that would indicate the the Intellitec is working, right?  The only other draw that I have on is the fridge @ 5 amps.  I will post my post my findings on the above in a little while.

Thank you for your help!

Carey

[ward_l_johnson]

The “other small electrical device” pictured in the original post is a PTCR, positive temperature coefficient resistor.  Its purpose is to very briefly (only a couple seconds) connect the compressor starting capacitor in parallel with the running capacitor.  The PTCR will have a very small resistance before the A/C compressor is energized, but the resistance increases dramatically after only a second or two, effectively removing the compressor starting capacitor from the circuit. Since you installed it from a working A/C I wouldn’t expect it to be a cause of your issue. 

[jacwjames]

Not familiar with Carrier AC units, what kind of controls do you have, is there a separate thermostat??  Is does is the display showing correctly???

[Idoc57]

2 hours ago, myrontruex said:

Did you take a voltmeter up there? You may not have 110 volts. The relays are likely run by 12 volts.

If you do not find 110 volts inside the AC unit you will have to go to your ac breaker panel and see if there is actually power coming out of the assigned breaker. And if it is there, move on through the load shedding relay board. 

If it is a load shedding issue you can temporarily bypass  that one control relay. 

Of course I'm typing away without knowing what rig you have but this might help. 

 

OK, 2006 Cayman it appears and it most likely has a load shedding device. 

OK Myron, here are my findings:

1.  No line voltage (120v) at the A/C unit

2.  Front A/C breaker is good

3.  When I check the voltage between neutral and each of the "RLY" (relay, I'm assuming) terminals and each of the "C.B." (assuming circuit breaker) terminals, all of the #2, #3 and #4 terminals (both RLY and C.B.) show 120v.  When I check the #1 terminals with the 20 AMP Front A/C breaker ON, I get 120v at the C.B.1 terminal and 0.5v at the RLY 1 terminal.  With the 20 AMP Front A/C breaker OFF, I get 41v at the C.B.1 terminal and the same 0.5v at the RLY 1 terminal.  

So, I am very hopeful that with your EXCELLENT knowledge and MUCH appreciated help we may have found the problem.  Now, if you would, please help me further by recommending the best way to get around this problem.  NOTE:  I do not nave a Washer/Dryer  

My first thought was to simply switch the wires from the #2 (W/D) terminals to the #1 (Front A/C) terminals since I don't have the W/D and really never use that dedicated W/D receptacle.  The only problem that I see with that is that looking at the 120v breakers is that it would cause both A/C's to draw off the same leg of the 50 amp main breaker.  So, I see two options:  1)  switch the #4 wires (water htr) with the #1 wires (frt A/C) and just use propane alone to heat water, or  2)  see if there is enough wire to switch the positions of the water heater breaker and the W/D breaker thereby keeping the loads balanced (well, at least not having both A/C's on the same leg).  Then I could just go back to switching the #1 and #2 terminal wires.

Please advise if you think this (option 2 above) would work or if you would recommend something else.

Thank you so much for your help!

Carey

1 hour ago, ward_l_johnson said:

The “other small electrical device” pictured in the original post is a PTCR, positive temperature coefficient resistor.  Its purpose is to very briefly (only a couple seconds) connect the compressor starting capacitor in parallel with the running capacitor.  The PTCR will have a very small resistance before the A/C compressor is energized, but the resistance increases dramatically after only a second or two, effectively removing the compressor starting capacitor from the circuit. Since you installed it from a working A/C I wouldn’t expect it to be a cause of your issue. 

Thank you, Ward

I had read something about a PTCR and I was wondering if that might be what that was.  I noted that the one from the rear air unit had the blue wire on top and the red wire on the bottom.  The one out of the front unit was opposite.  So, I'm guessing that polarity is not a factor on the PTCR???

Thanks,

Carey

1 hour ago, jacwjames said:

Not familiar with Carrier AC units, what kind of controls do you have, is there a separate thermostat??  Is does is the display showing correctly???

Jim,

These units do not have a separate thermostat, so I'm guessing that it is built into the unit itself.  You control it with a remote.  

Thanks,

Carey

[jacwjames]

As a temporary fix you could bypass the Intellitec all together and wire direct.  Just the two wires and wire nut them together. 

You would just have to manage the load yourself.   I did this when my board failed. 

[Idoc57]

4 hours ago, myrontruex said:

Did you take a voltmeter up there? You may not have 110 volts. The relays are likely run by 12 volts.

If you do not find 110 volts inside the AC unit you will have to go to your ac breaker panel and see if there is actually power coming out of the assigned breaker. And if it is there, move on through the load shedding relay board. 

If it is a load shedding issue you can temporarily bypass  that one control relay. 

Of course I'm typing away without knowing what rig you have but this might help. 

 

OK, 2006 Cayman it appears and it most likely has a load shedding device. 

Okay, I did some more thinking (that could be dangerous! 😉) about my post above.  I might be over-thinking this.  If I simply switch the two wires on the #1 terminals to the #2 terminals, and vice versa, I really haven't changed the amount of current draw off either side of the main breaker, have I?  All I would be doing is using a different set of relay an C.B.  The only thing that would be different is that the front A/C would shed off before the W/D, which wouldn't make any difference since I don't have a W/D.  

Please confirm what I just typed above.  I think my mind is getting "mushy"!  

Thank you so much!

Carey

5 minutes ago, jacwjames said:

As a temporary fix you could bypass the Intellitec all together and wire direct.  Just the two wires and wire nut them together. 

You would just have to manage the load yourself.   I did this when my board failed. 

Jim, please tell me what you think about my last post.  Does it make sense to you?  If it does, then I can maintain the load management.

Thanks,

Carey

My board is not bad, it is just the #1 relay.  The rest of them work fine as far as I can see.

[Idoc57]

5 hours ago, myrontruex said:

Did you take a voltmeter up there? You may not have 110 volts. The relays are likely run by 12 volts.

If you do not find 110 volts inside the AC unit you will have to go to your ac breaker panel and see if there is actually power coming out of the assigned breaker. And if it is there, move on through the load shedding relay board. 

If it is a load shedding issue you can temporarily bypass  that one control relay. 

Of course I'm typing away without knowing what rig you have but this might help. 

 

OK, 2006 Cayman it appears and it most likely has a load shedding device. 

As Reese Witherspoon said in the movie "Legally Blonde" ....."WE DID IT!!!!"

Thanks to everyone for your help, but a special HUGE THANK YOU to Myron for being spot-on with the solution!  I would not have even thought about the Intellitec Load Shedding Device as being the problem!  Myron, I thank you, MY WIFE THANKS YOU, and my two grandsons thank you.  You are THE MAN!  Our trip will be SO much more enjoyable now!  

One more testimonial as to how great this forum is!  You guys sharing your time and knowledge with the rest of us is appreciated SO much!

Carey  (aka "one happy camper")

[jacwjames]

So did you just swap the wires on the board??

 

 

[MyronTruex]

Looking at your EMS panel it appears you are on a 30 amp service????

If so, fire up the generator and see if the AC works then.

Not sure when that picture of the panel was taken but if it is possible the EMS was actually load shedding properly. Switching to 50 amp will disable the load shedding. 

The EMS looks at the power over about a three hour period and if the current is close to the 30 amp figure it will begin to shed. It will shed at around 24 amps loading.

I hope I didn't lead you down a path spending time on the load shedding. In any case, you are in a much better position with new knowledge.

If the relay is bad I would just wire nut the input and output of the relay circuit for that AC. You will become the "load shedding" device if you are on a 30 amp circuit and begin to trip it. 

I had to bypass all of my relays when my board went up in flames. 

[Idoc57]

1 hour ago, jacwjames said:

So did you just swap the wires on the board??

 

 

Yes Jim, I simply moved the pair that was on the position #1 terminals to the corresponding position #2 terminals and those that were on #2 to #1.  All I needed was a good relay to run my A/C power through.  Since I don't use the dedicated circuit for the Washer/Dryer, it doesn't make any difference if that circuit doesn't work.  

Thanks,Carey

Edited June 11, 2023 by Idoc57
merged responses

[Idoc57]

39 minutes ago, myrontruex said:

Looking at your EMS panel it appears you are on a 30 amp service????

If so, fire up the generator and see if the AC works then.

Not sure when that picture of the panel was taken but if it is possible the EMS was actually load shedding properly. Switching to 50 amp will disable the load shedding. 

The EMS looks at the power over about a three hour period and if the current is close to the 30 amp figure it will begin to shed. It will shed at around 24 amps loading.

I hope I didn't lead you down a path spending time on the load shedding. In any case, you are in a much better position with new knowledge.

If the relay is bad I would just wire nut the input and output of the relay circuit for that AC. You will become the "load shedding" device if you are on a 30 amp circuit and begin to trip it. 

I had to bypass all of my relays when my board went up in flames. 

 

38 minutes ago, myrontruex said:

Looking at your EMS panel it appears you are on a 30 amp service????

If so, fire up the generator and see if the AC works then.

Not sure when that picture of the panel was taken but if it is possible the EMS was actually load shedding properly. Switching to 50 amp will disable the load shedding. 

The EMS looks at the power over about a three hour period and if the current is close to the 30 amp figure it will begin to shed. It will shed at around 24 amps loading.

I hope I didn't lead you down a path spending time on the load shedding. In any case, you are in a much better position with new knowledge.

If the relay is bad I would just wire nut the input and output of the relay circuit for that AC. You will become the "load shedding" device if you are on a 30 amp circuit and begin to trip it. 

I had to bypass all of my relays when my board went up in flames. 

Myron,

That photo was taken today and yes I am on 30 amp service.  Once I switched the wires as mentioned in the post above, the Front A/C worked great!  We were so excited that we will have both A/C's working for our trip tomorrow.  You did lead me down a path alright, ....and it was the perfect path to fix the problem.  The thought of checking the Intellitec had not even occurred to me, so Thank You for educating me on how the load shedding works.  I may replace the board when I get back if they are available, but for this trip it looks like our problem is solved thanks to you.

Carey

[jacwjames]

X2 on what Myron indicates may be a possibility, if you were on 30 amp the board may have been shedding.  If you were watching the amps at the time it may have just decided to shed.  I seldom could run both my 13.5K BTU AC/heat pumps at the same time.  Any additional amperage usage pretty much limited me to 1 AC. 

Once you get done with your trip I'd suggest putting the system back to the way it was and do some testing. 

[Idoc57]

14 hours ago, jacwjames said:

X2 on what Myron indicates may be a possibility, if you were on 30 amp the board may have been shedding.  If you were watching the amps at the time it may have just decided to shed.  I seldom could run both my 13.5K BTU AC/heat pumps at the same time.  Any additional amperage usage pretty much limited me to 1 AC. 

Once you get done with your trip I'd suggest putting the system back to the way it was and do some testing. 

Jim,

I did not have both a/c's on at the same time. I agree with you , I don't ever run two a/c's when I'm on 30 amps. I'm pretty sure it was the power dropping out for only 2 seconds and coming right back on that overloaded the contacts in that number one relay on the board. I don't know if I can find just that relay and replace it or I might have to see if I can just buy a whole new board if they're still available. But honestly it serves me perfectly well, since I don't use the washer dryer circuit at all.

Carey

[MyronTruex]

I had no problem getting the board for my 2008 Endeavor.

As a side note, my panel is inside my closet in the bedroom. About two inches of space between the face of it and the closet door. Heat build up was tremendous inside the box and as an electronic tech I know that can cause real issues. And it did on mine. 

I had to leave the closet door open with the ac hitting the face of the panel to keep one of the breakers from tripping. The panel was extremenly hot inside when opened and finding a solution was difficult.

During a modifiation of my Water Heater, which is mounted below that panel, I discovered it was producing lots of heat that flowed upwards of course and added to the heat soaking. After the fantastic modification of installing a water mixer valve and higher temp sensors and increasing the size of the heater element I buried the tank in household insulation. The extra insulation virtually knocked out the added heat to the panel.

I did one other modificaion to the face of the breaker panel but will not discuss that here. 

[jacwjames]

I had a 750 model of the Intellitec system that was fried by lightening.

I ended up replacing with the 760 model that included new load meter and wiring harnesses.   There is a number printed on the board, do a search and you should be able to find one.