Rooftop AC/heatpump blower works but ac /heatpump does not

SOURCE: PROBLEM WITH DOMETIC RV ROOFTOP AIR conditioner

Check at the compressor terminals between the Red and the terminal for the overload protector to see if you are getting power to the compressor on startup.

Mike Butler

• 6674 Answers
• Posted on Aug 14, 2008

SOURCE: Coleman rooftop a/c unit, fan runs, compressor come on/off

First of all, Shut off power to A/C unit. !! Next,You need to remove the filter /cover ceiling assy, and with a flashlight, look way up inside and you'll see the cooling fins etc, that look similar to the back of the AC on the roof. If they appear dusty/dirty, then they need to be cleaned. I use a shop vac with a couple of extra extensions to reach, and duct tape a pot scrubber brush (half round or round with nylon bristles) to the extension. Then start as high as you can get on the fins, and come straight down, kind of like combing the fins, but not pressing super ******* them. Move over, and down again, until you get them all, or at least as much as you can. (Thats basically the same as your return air at home) I use the nylon scrubber because the brush attachment with vacuum is usually softer bristles, and doesn't get in there as well. If yours does, great.Make sure you wash out your foam filter in a little dish soap & water before you put inside cover/filter back up. Now to the best part, The upper unit on the roof. You need to remove the plastic cover, by removing the 4 screws holding it on, or if it's dometic type, screws all around near the bottom of the cover, and lift it off. The front of the colemans have a lip that the cover is down over, so you may have to pull cover forward & up, then it should all lift up & off. Here's a spot to be real careful, and ready for wasps & bees. Very few, if any that I've done over the years, haven't had a bees or wasps nest under them, so if you can do it on a cloudy day, or at least be ready to move quick, and have a wasp blaster spray with you, it may be smart. Just don't forget your on a roof when you start moving !! Another thing to remember too, is that the roof can be very slippery when wet, or dew is on it, so watch out!! Be careful !! Now with cover off, look at the fins on back of the unit, and clean those the same way, or spray with a garden hose, and soft brush, and clean them up. Next, look at the opposite side of those coils/fins, where the fan blade is in front of it, and lightly wash it down as best as you can with the hose, spray nozzle, and a brush if possible. Remember when using brush, up & down as much as possible, to avoid bending the fins over. If you can't brush it , just spray it as good as you can, to clean it. Water should not enter trailer, unless maybe if you go overboard with spray, and pressure. If you have access to an air-line to use up on the roof, that's good to, but a lot of times, the water will wash it down better. This will more than likely cure your problem, if you get it cleaned out. At the RV resort where I work as a Technician, we usually have a flat rate of approx. $50 CDN. for me to do it for you. 95% of the time it cures the early cut-out of compressor, and people actually report it cools better than it has for a couple of seasons. It has to be clean to do it's job properly. When those areas are dirty, the upper unit (compressor etc) has to work so hard to cool, it overheats & cuts out, until compressor cools down a bit, then comes back on, until it heats up too much again, and kicks out again. That's why it doesn't do it as much in cooler times, because compressor doesn't get as hot. Your also shortening the life of your unit too.

SOURCE: DuoTherm compressor starts but will not continue to run

check condenser fan if running. it will make compressor comes on and off if broken

SOURCE: We have a Coleman 7300 rooftop ac unit. When the

The fan motor is getting hot and going off on the internal overload in the motor.
This is caused by either a low voltage, a bad capacitor, or tight or dry bearings in the motor.
To check the bearings turn the power off to the unit, then spin the fan blade if it spins freely then the bearings are ok.
To check the capacitor you will need some kind of
tester or you can buy a capacitor and replace it, that's what a lot of people do. They usually don't cost very much.
To check the voltage you will need a voltmeter and measure the volts at the unit.

SOURCE: coleman 7300 rooftop air conditionor wont operate

When they sit allot - sometimes the fan will stick.. Take the cover off,, turn it on and see if the fan is stuck.. Spin it by hand to free it up..