Would Defective Air Cond. Blow Cold In Cool Weather?

[goreds2]

OK, I am getting ready to look at a Class B on Friday. It is being sold via an estate and the son is doing a very good job at answering all my questions before looking at it. I asked about the Roof top AC. He said he plugged it in and turned it on tonight. He said it blew cold but thought it may be because it is cool outside tonight as it is 60 degrees. I think he is doing his very best to be honest. His father and not him used it through the years.

Would a defective roof top Air Cond. unit blow cold if it is 60 degrees outside? I would not think so. Thanks,

1990 Dodge Ram 250

[leslane]

That depends on the ambient temperature and your definition of "cold". The A/C unit will blow ambient temperature if it is not working, therefore if it is 60 degreess outside it will blow 60 degrees, plus or minus a couple of degrees, air through the vent. If it is 100 degrees ambient, it will blow 100 degree, plus or minus a couple of degrees, through the vent. Listen for the compressor to come on when the A/C is turned on to the lowest setting. If the unit starts up and it still does not blow cooler than ambient then the A/C unit needs service.

[Mike]

I'm no HVAC expert but, if it were me going to see this van, I'd fire up the AC, and set it 10
degrees (if possible) below whatever the outside air temperature is. I would think it should
keep running and trying to get the inside air temp down to that setting (if the thermostat is
working). Then after a while, maybe 5-10 minutes or more, I'd just put my hand in front of
the blower/vents, and see if it feels significantly colder, than the rest of the inside air.
Most class B sized rooftop AC units are the recirculating type, I think, so they shouldn't be
pulling in very much outside air, as far as I know. You could check and see if your particular
unit/type has a "fresh/recirculate" control, like your dash air conditioning. If it does allow
outside air in, set it to recirculate first.
That's what I'd do.

[renrut]

Most air conditioners have outside temperature sensors to control the compressor. If the outside temp is too low, it will prevent the compressor from coming on. Even a car's dash air has this. When it is too cold, the oil inside the compressor will be thick and running it can damage the compressor.

The easiest way to test the unit is to turn it on and crank the thermostat down. If the compressor turns on and stays running, it is a good sign. If it turns on and off and cycles like that, it usually indicates low Freon. If the outside temp is 60, that isn’t too low and the unit should run.

Check the temperature coming out of the unit when it is running. It should be about 40 degrees “F” or cooler.

[obiewan kanobe]

start the van and turn on the heater all the way up. let the van get real hot inside. then shutoff the van and heater. plug in the ac and turn the air cond to max, full fan and see if it cools. this has always worked for me. i have not encountered any cold switch in 52 years of messing with cars, but, if it really has one, the compressor will not run. if you are familiar with electronics, find any such sensor and short around it.

[goreds2]

Thanks everyone, I will check it out today.

[goreds2]

Just updating some of my posts since it has been a few months. The dash air probably needs recharged in the future.