June 24, 2018, 02:39:12 PM

Author Topic: MCI over the road AC question? UPDATE  (Read 7018 times)

Offline Nick Badame Refrig/ACC

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Re: MCI over the road AC question?
« Reply #15 on: April 24, 2009, 06:08:32 AM »
Jason,

Whatever is wrong with your bus must be contagious. When we first bought our bus a year and a half ago the air was really, really cold and slowly last summer it started to be less and less cold. I pulled the filter this spring and it was covered in dog hair, so I figured when i cleaned it the air would work fine. No such luck. On a test drive yesterday it blew warm, almost hot air. I checked the sight glass in the condensor compartment and it shows halfway up the sight glass but that is with the engine off and on a healthy driveway incline with the bus nose downward.

Do you check the sight glass on flat ground with the engine running and the ac on???

My next question is, do we ever stop spending money on these things we call buses??

I need a good old healthy gambling addiction...  just kidding. I gripe but I love my bus and the freedom and joy it brings my family.

Good luck Jason and if you find the problem keep me informed and I will do so for you as well.

Rick

Hi Rick,
Only check the sight glass when the system is running.  You should have flow, with or without bubbles..

Nick-
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Offline bottomacher

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Re: MCI over the road AC question?
« Reply #16 on: April 24, 2009, 06:24:16 AM »
A quick look at the book shows no reset switch. There is the 100# low air switch, and the high and low pressure switch, both located on the top of the compressor. FWIW

Offline JackConrad

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Re: MCI over the road AC question?
« Reply #17 on: April 24, 2009, 07:40:03 AM »
A quick look at the book shows no reset switch. There is the 100# low air switch, and the high and low pressure switch, both located on the top of the compressor. FWIW

The low air switch is in the Penn switch box that is on the outside of the rear electrical panel ()at least that is where it is at on our MC-8). This switch prevents the AC from working until the you have air pressure. This same switch also prevents the alternator from charging until you have air pressure.  If the alternator is working properly, I doubt if this switch is the problem.  Jack
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Offline jmblake

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Re: MCI over the road AC question?
« Reply #18 on: April 24, 2009, 10:00:12 AM »
The alternator is working fine, The high & low preasure switch would that be in one of the two junction box's mounted on the side of the compresor? Jason

Offline bottomacher

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Re: MCI over the road AC question?
« Reply #19 on: April 24, 2009, 11:23:04 AM »
The book says the pressure switches are mounted directly on the compressor body.

Offline junkman42

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Re: MCI over the road AC question?
« Reply #20 on: April 24, 2009, 07:16:24 PM »
Jason, I looked at My notes and here is what fixed My OTR air.  If You have the mci prints for the bus air, there is a relay that is controlled by a device they call a sensing unit, in reality it is a thermistor that controls relay cr1.  I am forcing cr1 on by bypassing the thermistor with a toggle switch.  I am to cheap to buy the sensor.  I once had a problem with  the compressor solenoid valve which controls how many cylinders of the compressor gets used.  Jumping the thermistor will not hurt anything, the air will start making cold air or not.  Not much help I know but might help.  Regards, john

Offline RickB

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Re: MCI over the road AC question?
« Reply #21 on: April 25, 2009, 06:08:43 AM »
Well Jason I told you i would let you know if I made any progress and yesterday my AC started working again. IU'm not really sure why, the only thing I did was turn the temp control dial to full cold but I have doubted whether that thing is even hooked up. Sorry I can;t be more specific all I know is it is working and I am grateful
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Offline jmblake

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Re: MCI over the road AC question?
« Reply #22 on: April 25, 2009, 08:08:00 AM »
Rick Happy yours is working, Mine still will not work, I took my temp control out of the return air duct and it looks very clean, I heat light on the dash works normal when you turn the heat up it comes on and turn it down it goes off so I think it is working, My AC guy must be away for the weekend so Ill try him again the first of the week. Until the Iam going to keep checking things out. Jason

Offline jmblake

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Re: MCI over the road AC question?
« Reply #23 on: April 25, 2009, 01:49:31 PM »
Don't know if this may be part of problem but this is the 2 junction boxs mounted to the compresor in the first pic the 2 terminals on the left have voltage to both terminals and they are for the Lb presure cut in & cut out, now the 2 terminals on the right only the bottom terminal has voltage the top has none and it is marked High pres cut out and is set at 250, I turned it up to 300 and down to 200 and still no conection. Question should there be power to both terminals for the compresor to work? and how far can you turn them up or down or can I jump the two to see if it works? then the second pic is the other junction box and both terminals have power also. Thanks Jason

Offline Nick Badame Refrig/ACC

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Re: MCI over the road AC question?
« Reply #24 on: April 25, 2009, 03:39:41 PM »
Hi Jason,

Think of the psi devices as switches. They mearly complete a curcuit. If you remove the wires from the terminals,

you should have continunity through the switches [from one terminal to the other]. If not, it may be faulty or open for a reason.

Good Luck
Nick-
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Offline jmblake

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Re: MCI over the road AC question?
« Reply #25 on: April 25, 2009, 05:11:01 PM »
Well I just got back home and decided to try and jump the switch and still nothing, Ill have to wait and get the freon checked next week and see what happens. I don't know anything else to try. Thanks a bunch guys for all your help. Jason

Offline RickB

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Re: MCI over the road AC question?
« Reply #26 on: April 26, 2009, 04:38:30 AM »
Jason,

This may sound rudimentary but have you cleaned the filter lately?

It is in the front start battery compartment. Big ol' thing. Just a thought...

Good luck,

Rick
I will drive my Detroit hard... I will drive my Detroit hard.

Offline jmblake

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Re: MCI over the road AC question?
« Reply #27 on: April 26, 2009, 05:58:56 AM »
Rick
Yes, I cleaned the filter, The compresor just isn't kicking in. Thanks Jason

Offline jmblake

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Re: MCI over the road AC question? Update
« Reply #28 on: May 20, 2009, 06:16:15 PM »
Well finally got my AC guy over It's a busy time and we found a leak in one of the pressure valves on the compressor so he is going to order a new one and put it in next week, But after he left I went to shut the condenser door and heard a hiss coming from there to, I'll have to get a hold of him tomorrow again, it is coming out of the can where the sight glass's are there is a piece coming out of the can that has a slotted end in the end like for adjusting something and there is 2 small hole's on the side of it where it is leaking from. Any body know what this is? Thanks Jason

Offline Nick Badame Refrig/ACC

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Re: MCI over the road AC question? UPDATE
« Reply #29 on: May 20, 2009, 07:48:48 PM »
Hi Jason,

The valve on your compressor that is leaking is an unloader valve and this valve may leak if the system is overcharged.

Sometimes they go bad but, just make sure you have the proper amount of refrigerant in the system.

The piece comming out of the canistor that you discribe in the condencer comp. is also a safty.. It's a "fuseable link" It will also

purge refrigerant if overcharged..

Jason, if you need to call me tomorrow, 609-263-2296 office

Good Luck
Nick-
Whatever it takes!-GITIT DONE! 
Commercial Refrigeration- Ice machines- Heating & Air/ Atlantic Custom Coach Inc.
Master Mason- Cannon Lodge #104
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