Hi,
This summer I noticed that my front rooftop A/C unit would not run on Low Cool? It works fine on High, but when I turn it to Low, it shortly shuts itself off. It also sounds like it is suddenly pulling a lot of current. These are Carrier Air V units and long since discontinued. Does anyone know any place that can still service these?
Also, and more relevant to this post: I was doing some research online and found an ebay vendor selling "hard start kits" for these and other rooftop units. They claim that these will help eliminate the sudden big draw of current when the compressors cycle on. I assume they use capacitors to help accomplish this. Do these really work? How are they installed? How do I know if the units I have already have them?
Thanks,
Jim
When running any roof top air when the outside temp is over 90, you should only run it on high since most roof tops use just one motor for both the condenser and evaporator fans. What is happening is on low, the fan on the condenser side is not pulling enough air over the condenser causing a too high pressure situation-thus shutting done the compressor to protect it. You might want to check the outside condenser to see if it is clean. Dirt build up can cause less then efficient cooling on low fan. Good Luck, TomC
Thanks Tom, I've had both covers off this spring and all is clean. It doesn't seem to matter what the outside temps are, the front unit will not run on low cool. It will run on low fan.
What do you know about those hardstart kits?
I have used Hard start kits, many times, seemed to solve the problem. maybe it just made me think so but it is still working today, Nick Badame would be the one to know the real answer, he is a BCM Board moderator, AND a Rocket Scientist when it comes to heating and cooling, Now he's getting pretty old now and may take him some time to respond, But you can bank on his advice,
I know enough to be dangerous when it comes to electrical but I thought the Carrier and Coleman had a start plus a run capacitor so what good would a hard start capacitor kit do for you for a AC not running on low ?
Does the compressor run on high but not on low-or does the compressor run for a while on low then kick out? If it runs only on high, but not on low, you have a bad fan switch. Good Luck, TomC
Luvrbus: I know enough to be dangerous when it comes to electrical but I thought the Carrier and Coleman had a start plus a run capacitor so what good would a hard start capacitor kit do for you
Good point. That's the main reason I haven't tried it on my units - I don't know that they do not already have one! Any clues in that direction would be very much appreciated.
TomC: Does the compressor run on high but not on low-or does the compressor run for a while on low then kick out? If it runs only on high, but not on low, you have a bad fan switch. Good Luck, TomC
If I turn the unit ON with the switch in High Cool - the unit will run fine for as long as I need it. If I turn the unit ON with the switch in Low Cool OR I switch the unit to Low Cool while it is running on High Cool, it seems to run for a few seconds and then the entire unit switches itself off. I can run the unit on Low Fan - no problem, but as soon as I turn it to Low Cool, it runs a few seconds and then shuts down. It sounds like the compressor tries to start, but then everything stops.
Thanks!
Sounds strange-but take a look at your circuit breaker at the breaker box for the A/C and see if the screw pinching the wire to the breaker is tight. I had one come loose and create a smoking situation. We have to tighten things up every so often since, even with air suspension, everything is vibrating going down the road.
When the unit cuts out-does it blow the circuit breaker? Good Luck, TomC
wire to breaker connection is tight and it does not blow the breaker when it shuts down.
I have never heard of an A/C compressor that was variable....the fan yes....sounds like a bad switch somewhere.
Hi Jim,
From all the good advice you have received as of now and your input, I suspect that your
internal overload cut-out device inside your compressor has weakened or your compressor
has internal winding problems causing high current draw. If either has happened a hard start kit
may not be of any help because this is not a compressor starting issue but a running one.
The internal overload works off current draw and kicks open when the current exceeds a factory
preset to prevent a short and or fire.
(Bill, yea I'm getting old (almost 50) but I'm also getting too busy to be old. ;)..)
Nick-
Thanks Nick I thought the starting capacitor just started the compressor then dropped out of the loop I just didn't know how to explain it
Thanks Nick, Tom, Cliff and everyone else for your advice.
If I read between the lines correctly, this is not something I am likely to be able to fix or have fixed. So I should just use it until it fails and then replace the whole unit??
This is the nice thing about roof tops-you can replace them in about 2 hours. I would suggest you look at the DuoTherm Penquin. They have a three speed fan which is nice to have for quieter night time use. About $800. Good Luck, TomC
I think the Penguin has been replaced by the Penguin 2 that is what I had to buy and watch it they forget to tell you it has only 2 speeds now
It's shame about Carrier leaving the market that was the best roof air on the market IMO for blowing cold air
Like every thing else since the Penguins are made in Mexico now their components are made in China and other countries nothing on the new one I bought is made in the USA not even the shipping box lol
Nick, I knew you could do it, and yes you are busy, I follow your facebook post, you certainly have moved WAY up in the Bus conversion world, I am glad for you, But it shure would be nic if you could come back down to the lower levels and visit with some of us in Arcadia,.