air conditioners

[ouachitah1]

My last two outings I've had trouble with the ACs on my 2003 Country Coach Intrigue. When I leave home where I'm plugged into 50 amp, I turn on the generator, then the AC, then unplug the shore power. The AC units function fine during the trip. When I get to the campground, I turn off the AC, turn off the generator, and plug into 50 amp shore power. After the internal surge protector fips over and electric comes into the coach, I turn on the AC but the compressors don't start. The fans work fine. I've tried resetting the comfort control unit. Tried using generator power again. Checked all the circuit breakers. Nothing helped. I used fans during the night. In the morning I turned on the AC and they both started right up and worked perfectly all weekend. Has anybody has this problem?

[ouachitah1]

Thanks, Fred. A very helpful explanation.

[dougrainer]

Golden_HVAC wrote:

ouachitah1 wrote:
I will try leaving more time when changing power sources and setting the temp high during the power switch is a great idea. Still shouldn't they have turned on after waiting an hour or two. I had to wait overnight before the AC would turn on again.

If the compressor power is interrupted by say 1 second to 2 minutes, it can cause a strain on the compressor when it re-starts. The compressor circuit itself does not have a time delay, it is in the thermostat. However most thermostats are not smart enough to know if there is a 120 volt power loss at the compressor. So the thermostat will see 12 volts input (so it can run the furnace as well as both A/C units) and not detect the loss of power like a home furnace will do.

If you turn off the thermostats manually, and leave them off for say 10 seconds, then the internal time delay will be activated, and it should not turn on the cooling for at least 2 minutes. So setting it to 85F for when you start the generator, and then back to 70 as you return to the coach after unplugging the RV is plenty of time for the compressor to be off between run cycles.

Without the off time, the compressor can draw an excessive amount of amps, and will trip a internal compressor amperage overload. Then the compressor has to cool off, and then it can reset once below about 130F. This can take 10 - 15 minutes!

Good luck,

Fred.

The compressor start delay (2 minutes and 45 seconds) is built into the CONTROL Board on the AC,not in the Tstat circuit. Doug

[2oldman]

ouachitah1 wrote:
shouldn't they have turned on after waiting an hour or two.

Yes. Is the CG voltage low?

[Golden_HVAC]

ouachitah1 wrote:
I will try leaving more time when changing power sources and setting the temp high during the power switch is a great idea. Still shouldn't they have turned on after waiting an hour or two. I had to wait overnight before the AC would turn on again.

If the compressor power is interrupted by say 1 second to 2 minutes, it can cause a strain on the compressor when it re-starts. The compressor circuit itself does not have a time delay, it is in the thermostat. However most thermostats are not smart enough to know if there is a 120 volt power loss at the compressor. So the thermostat will see 12 volts input (so it can run the furnace as well as both A/C units) and not detect the loss of power like a home furnace will do.

If you turn off the thermostats manually, and leave them off for say 10 seconds, then the internal time delay will be activated, and it should not turn on the cooling for at least 2 minutes. So setting it to 85F for when you start the generator, and then back to 70 as you return to the coach after unplugging the RV is plenty of time for the compressor to be off between run cycles.

Without the off time, the compressor can draw an excessive amount of amps, and will trip a internal compressor amperage overload. Then the compressor has to cool off, and then it can reset once below about 130F. This can take 10 - 15 minutes!

Good luck,

Fred.

[ouachitah1]

I can try plugging into shore and waiting for the surge protector to flip over before turning off the generator. If I set the temp high and don't turn off the climate control, it might work. Thanks.

[ouachitah1]

I will try leaving more time when changing power sources and setting the temp high during the power switch is a great idea. Still shouldn't they have turned on after waiting an hour or two. I had to wait overnight before the AC would turn on again.

[2oldman]

Golden_HVAC wrote:
You might not have waited long enough between shutting off the generator and plugging into the campground power..

x2

Upon arriving, can you plug in Shore before shutting off gen?

[dougrainer]

Does your unit have the Intellitec or PCS EMS (energy management system)? If so, on the hi line units, they usually had the compressor lock out instead of just killing 120 power to the complete AC unit. This means in certain conditions the compressor power will be locked out up to 15 minutes or so as the EMS evaluates the available 120 power coming in the unit. IF this is happening the remote panel for the EMS will show compressor shed on the affected AC units. The fans will still run. Doug

[newman_fulltime]

they have protection built in them if you shut them off in a cycle and loose power when the come back on they take 5 minutes to come back on it is for regulating the head pressure

[Golden_HVAC]

You might not have waited long enough between shutting off the generator and plugging into the campground power. Then you would need to wait about 6 minutes before turning the thermostats to 'cool'.

You can turn on the fans right away when you plug in, they have no problem restarting. But the compressor needs to be off for about 3 minutes - 6 minutes is much better. If the fan keeps running, all the better.

As for starting the generator before unplugging at home, while it is 'safe' you probably should also let the compressors be off during the transition time, or they might lose power for 1/2 second, and restart before stopping. If you just set the thermostats to about 85F for the 5 minutes while you are starting the generator and unplugging from your home or campground, it will work fine. Then after the 5 minutes is over, set the thermostat to the desired temp.

Good luck,

Fred.