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Carrier apu troubleshooting

Apu has no power to controller wont do anything is there a reset or what to check first

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Check the breaker

Posted on Apr 15, 2014


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Carrier apu blows cold air for twenty seconds and fan quits engine keeps running and fan starts again but only blows cold air for another twenty seconds

Have you tried rebooting the system? Just turn off the breaker for a few minutes.If you need more questions for your Air Conditioning Repair needs, check us out online.

Jul 07, 2017 | Carrier Heating & Cooling

1 Answer

I have a carrier comfort pro apu.When I turn on the heat to high it kicks the hvac breaker but runs fine when the heat is on low. What would cause that to heppen.

1. Breaker/wiring too small. Check rating plate, and breaker. Do not replace breaker with larger one without making sure that the wires are large enough to carry the amp load. 2. Shorted high voltage wiring. Check for burned or bare wires.

Jan 04, 2016 | Carrier Heating & Cooling

1 Answer

I have a carrier apu unit when I torne on it tor of and it says unit onder vortage

Are you on shore power or generator or an extension cord? Low Voltage could be caused by to small wiring.

Oct 09, 2014 | Heating & Cooling

1 Answer

Carrier apu troubleshooting

there are lots of reasons compressor blown, capacitor not working, contactor not being pulled in, thermostat notworking, and i can doon and on

Aug 17, 2014 | Heating & Cooling

1 Answer

My comfort pro 6000 apu screen said low voltage and ac wouldnt work

1.Need to check the generator belt to make sure it's not lose or broke.
2.Remove bottom inspection cover and use a fluke meter and check for 110 at generator.
Those two thing's would be where I would start for the low voltage alarm. now for the a/c alarm. There could be multiply thing's to cause the a/c not to work. Do you have and functions on the driver control panel? I would start.
1. Remove the top cover on the APU. Check the 20 amp fuse. If the fuse is blown it will cause you not to get voltage to the CCU board witch could be a reason the a/c is not working. Also if the fuse is blown the first place to look would be the condenser fan on back of the truck. You can use a fluke meter and ohm it out. Don't quote me but I believe it ohms at 10.4 I'd have to look in the book. also use a screw driver and see if the blade is spinning freely it is very common for these to lock up and blow the 20 amp fuse. You can remove the top cover on the CCU under the bunk. There are 4 3/8 bolt's. There should be a little green service light flashing. Then start the APU and there should be green light's light up these light's are your input lights meaning you are getting voltage. When you chose a function on the driver control panel there should be orange light's light up witch would be your output light's. these light's wont come on if the 20 amp fuse is blown. If you need more information I'm willing to help just ask.

Nov 07, 2013 | Carrier Heating & Cooling

1 Answer

Carrier APU wont shut down and showing SP on screen?

Hi there I have seen this a few time's while working on them. The SP stand's for shore power. If you can't get APU to shut down remove the top inspection cover. There is a lever by the fuel solenoid you can push and hold and it will shut the APU down. Do you know if the APU is equipped with shore power? If not I had one do this to me after I power washed it off. If you remove the top cover on the APU on the back wall on the left had side there is a controller. This is called your APU controller. There are to plug's in controller. remove them and check the weather stripping on the plug. I have seen them leak and let moisture in there and it would cause the APU to do funky thing's. If not it's possibly a APU controller. I'd check them few thing's and if you still can't determine a problem get back with me and we can diagnose further.

Sep 21, 2013 | Carrier Air Conditioner Accessories...

2 Answers

Carrier comfortpro apu wont start says main engine interlock

Ignition switch to vehicle needs to be in "OFF" or "Accessory" position before you try to start the unit.

Mar 13, 2012 | Cars & Trucks

3 Answers

Apu starts fine but no fan no heat and no air conditioning and no 120 volt.

Hi there, Would this be a preheat / comfort pro APU? If so I would start with removing the top cover on the APU. There will be a fuse holder with a 20 amp fuse on the back wall on the left side of the APU above the APU controller. Check and see if the fuse is blown. If it's not then the CCU board under the bunk/ bed isn't seeing power. Either 12v harness or the communication harness both from the APU controller to the CCU board are rubbed on the frame, or the CCU board isn't transferring power properly. The CCU board is under the bunk. There are 4 3/4 bolt's that hold the lid on. Start the APU and look at the board you should have green light's light up. these light's are called input light's. Then chose a function on the driver control panel as in heat, a/c, low or high fan and see if they come on. If the driver control pane are showing the function on look down at the CCU board and see if there are orange light's on. these light's would be your output light's. There's a lot of cause's for this problem if you need further help feel free to ask. Thank's

Nov 08, 2010 | Carrier Heating & Cooling

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