Roof top A/C

crazytruckin

Expert Expediter
Is there anyone out there installed who has had a roof top air conditioner and diesel gen set installed on their straight truck? Need help/advise to do this. Seems this would be cheaper and more efficient that the expensive APU's out there. Thanks
 

P51bombay

Expert Expediter
Might be cheaper but not by a huge margin I think. I guess it depends on what generator you got, I looked at some Onan prices and even the smaller ones are nearly $6000. I do like the concept though, seems much simpler to have a stand alone heater/AC unit that is fairly cheap, the Coleman ones I was pricing seem to run around $600 and at that price its hardly even worth fixing if something went wrong - just slap a brand new one on and be on your way.
 

always confused

Seasoned Expediter
i have a coleman ac with heat strip on my sleeper. works good, will freeze me in no time and managed to keep things defrosted if not toasty at 20 below. the heat strip is only 1200watts.
that makes it a little anemic when things get below zero.
i went with a gas rv generator. mine puts out 3600 watts. more than enough to run ac, tv, ref, and microwave at same time. gen is very quiet which i like. yes i have to stop at a gas pump every couple days, but for me I find its not a great inconvience. the gen runs about 4 hours on a gallon of gas. price of gen about 1500.00, price of ac about 600.00 gas tank, side box, misc fuel line, electric connections, mounting bracket for gen less than 500.00.
installed everything myself, with a little help from my neighbor to get the ac on the roof.


note: the ac broke during the first year. the compressor came loose from its mount breaking the lines. coleman replaced the unit under warrenty. had the new unit modified. the compressor is held on the mount by a couple butterfly push tabs. these had vibrated off allowing the compressor to bounce off the mounting pins. a couple of small holes drilled in the mounting pins and two cotter keys keep the butterflys from popping off.


based on current fuel prices i figure unit has paid for itself already. its been on the truck for two years this month.
 

crazytruckin

Expert Expediter
To "always confused": Thanks for your reply. Where did you mount the generator and gas tank? Just wondering about the safety of having a gasoline tank on the truck.
 

x06col

Veteran Expediter
Charter Member
Retired Expediter
US Army
Whattt???? Do you think there NO gasoline powered trucks on the highways?????

Git back!
 

always confused

Seasoned Expediter
To "always confused": Thanks for your reply. Where did you mount the generator and gas tank? Just wondering about the safety of having a gasoline tank on the truck.


generator mounted under box on right side of truck. gas tank is inside side box mounted under box on the left side. used a steel gas line inside a piece of wire conduit to get from one side to the other. heavy duty plastic protects the line and prevents chaffing. a few heavy duty zip ties and various cable clamps keep everything in place. a hole in the floor of sleeper provided access to inside of sleeper. regular household outlet provides distribution point for power. a few feet of heavy duty extension cord does the rest. i also have a power inverter connected to the truck batteries mounted on the floor by the outlet. this allows me to plug into the inverter while driving for power to ref and stuff in sleeper. this is nice when conditions are such that heat or air aren't needed. can use ac stuff in sleeper for a few hours off battery power. no engine idling, no generator. just keep in mind if you run the batteries too long the truck won't start....
 

maybe_driving

Seasoned Expediter
ProductOPTI

These guys have a generator for 999.00 that is diesel. Looks like you could move the control panel to the inside and add wire back to the gen set not sure how you would get fuel to it maybe add a small pump.
 

always confused

Seasoned Expediter
ExpeditersOnline.com Expedited Trucking Owner Operator Careers and Truck Sales

These guys have a generator for 999.00 that is diesel. Looks like you could move the control panel to the inside and add wire back to the gen set not sure how you would get fuel to it maybe add a small pump.

please notice there is no enclosure for the alternator, or control circuits. moisture is not your friend when it comes to electronics. this unit would need to be in some type of enclosure or will probably have a very short lifespan. looks like a gas generator i got for the house. parts made in china, assembled in mexico. unit was non functional on arrival. they sent some parts which i installed and it worked for awhile. then it quit. found alternator leads had become entangled with rotor and ripped out. managed to repair it. basic cheap construction, but i got what i paid for... a cheap gen for use around house, barn, and pasture.
 

crazytruckin

Expert Expediter
Thanks guys for your input. Mounting,wiring,fuel tank,gen set (diesel or gas) a lot to consider. Getting it done's the hard part but with all the idling laws popping up, it seems like a neccesity. Thanks again.
 

tru2037

Seasoned Expediter
A good roof top takes a LOT of power, which is what ONAN QD's are great for, but they are $$$. The 5500 onan struggles to power the coleman roof top, 5500=5.5kw, so even a smaller generator might make you regret not going all out.
 

greg334

Veteran Expediter
Most of these A/C units draw 15 amps, with maybe a 25 amp surge on start up - that is the top end.

With a 5500 watt generator, the A/C has to have a surge of way beyond 45 amps with a running current at 35 amps to slow it down.
 

ebsprintin

Veteran Expediter
And with all those idling laws popping up, keep in mind that you may be building a system that will be illegal to operate. --eb
 

greg334

Veteran Expediter
Yea that's a good question, why?

Carb officials said "if they use diesel engine APU's, then they have to conform to our standards. But if they use Gas generators, that's alright with us".

I am wondering if anyone out there actually has their roof top on the cab.
 

P51bombay

Expert Expediter
Yea that's a good question, why?

Carb officials said "if they use diesel engine APU's, then they have to conform to our standards. But if they use Gas generators, that's alright with us".

I am wondering if anyone out there actually has their roof top on the cab.


SO you can use a 2 stroke powered generator and that would be OK?
 
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