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Front AC slow to start??

August 25, 2016, 10:45:11 am

My front AC unit on a 2001 320, took several minutes to start last week and then started OK several times.  This week it won't start??

Any ideas??  I am thinking capacitor??  Any ideas on the part number before I have to get my mountain climbing kit on??

Speedbird 1

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Re: Front AC slow to start??

Reply #1 – August 25, 2016, 11:03:19 am

Quote from: speedbird1 – August 25, 2016, 10:45:11 am

Any ideas on the part number...

When asking this type of question, it is helpful if you provide as much info as possible, such as Make and Model of the A/C unit

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Re: Front AC slow to start??

Reply #2 – August 25, 2016, 02:28:38 pm

There is a two minute delay in our compressor start on our dometic

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Re: Front AC slow to start??

Reply #3 – August 25, 2016, 05:04:28 pm

Thanks Bob,

My rear one starts almost immediately and I just timed the front one and it took exactly 2mins just  as you said.  Live and learn

Speedbird 1

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Re: Front AC slow to start??

Reply #4 – August 25, 2016, 05:14:35 pm

Do you mean the fan or the compressor?  Fans start first (as soon as I switch the system on at the thermostat), sequentially from back to front on mine, then the compressors start sequentially from back to front a couple minutes later. 

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Re: Front AC slow to start??

Reply #5 – August 25, 2016, 05:24:03 pm

 Sounds like you have a bad potential relay.The compressor should start right up after it's been off. There could be a delay timer but usually they only come into play if you have a intermittent power loss to keep the compressor from hard starting and overheat the windings.

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Re: Front AC slow to start??

Reply #6 – August 25, 2016, 06:45:11 pm

When fans come on with the dometics in the 2001 coach depend on how you set the fan controls on the five button control. 2-3 minutes delay before starting is about normal. 

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Re: Front AC slow to start??

Reply #7 – August 25, 2016, 09:50:39 pm

With my two units the back one comes on with the compressor almost immediately it is selected whereas the front one take exactly 2mins and the compressor is also on at that time.

You have me thinking now, that I may have changed something while messing with the thermostat panel?

Speedbird 1

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Re: Front AC slow to start??

Reply #8 – August 25, 2016, 09:58:37 pm

Is the unit trying to start, as in, can you hear it humming.  Sometimes the bearings on these units get dirty and become more resistive to starting.  The colder the unit is, the more resistance there is.  I have had to open the unit to get to the motor and then oil the bearing from the outside.  Use a good oil, not wd-40 or the like.  You may be able to rotate the fan blade from below to see if it turns hard.  Have a great day  ----  Fritz

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Re: Front AC slow to start??

Reply #9 – August 25, 2016, 11:03:21 pm

A good point.  I must get up there and check the fans rotation and lube if needed.  May just be the simple solution.  It has been warm here for the past couple of weeks so a low temperature is not the cause.

Speedbird 1.

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Re: Front AC slow to start??

Reply #10 – September 19, 2016, 05:45:02 pm

Just a few days ago I thought my own front AC was having a lagging start. Something would kick on, then it would hum for a minute or two, then the cool air would start coming out. Couldn't remember if this was normal or not.
As of today, when Houston is having a heat index over 100, it's decided not to send out any cool air at all (although the back unit seems to be operating just fine: click, brief hum, cool air). The front AC reminds me of a car that wants to turn over and tries, but then just gives up.
I'm in a 1998 U320 (new to me since June 2016). Seems the AC units are Dometic and there is a dual-zone thermostat behind the driver's seat.
Clearly, something needs to be fixed, but I'm not sure what I can do or what I need someone else to do. Am willing to climb up on top and do something, but haven't the foggiest where to start or what tools I should take up there (and frankly would prefer to wait until tomorrow morning if I can - the indoor-outdoor is reading 97F in the shade.
In the meantime, should I shut off the entire AC unit from the control panel to prevent something from frying? Or am I too late with that? Or can the back AC function just fine for the time being?
All help appreciated.

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Re: Front AC slow to start??

Reply #11 – September 19, 2016, 05:51:19 pm

The two A/C units are totally independent.  So, if the front one is inoperative, you can still run the rear one.

As far as getting the front one back on-line, you may need an RV repair guy to diagnose it. Could be something as simple as a loose wire, or could be a bad unit.  If in Houston, cheapest place for replacement units is PPL.

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Re: Front AC slow to start??

Reply #12 – September 19, 2016, 06:10:31 pm

Many thanks, Wolfe10. At least now I won't worry about the back one for the time being. I believe PPL is closed down for the day by now, but I can see about getting some attention tomorrow.

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