3720 Cab A/C Problem??

[sunnyside360]

Hello all. I've been using the A/C which works fairly well but today I noticed a lot of water condensing on the rear third of the roof and water constantly dripping down on the front and rear windows. Is this normal for the 3X20 series with cab when using the A/C?? Thanks.

 

[DrainPondDesign]

Inside or outside?

During high humidity the outside of the glass will get cold enough to condense moisture & you have to choose between raising the inside temp until above the outside dew point or living with the condensation.

Inside it should not be condensing as the coldest the air gets is right at the evaporator (cold deck) where air moisture should condense & be drained to the outside. Once in the cabin the air will get warmer & be above its dew point.

At least that is the theory.

Of course if you are wet or evaporating a lot of moisture then that might cause condensation until you dry off or cool down.

Stay cool

 

[JasonMac]

Also You may want to check your air filter (above the rear window) and make sure it is not clogged of dust and grass clippings. I usually take mine out and bang it after some heavy duty brush hogging (especially on a very dry day). It does collect a lot dirt. I'm about to buy a few back up filters, just so I have them on hand. But you can usually self cleand those air filters quite a bit before you have to buy new ones.

Yeah, so I would take out the filter every once in a while and bang it out (like you would if you were cleaning chalkboard erasers.

 

[sunnyside360]

Inside or outside?

During high humidity the outside of the glass will get cold enough to condense moisture & you have to choose between raising the inside temp until above the outside dew point or living with the condensation.

Inside it should not be condensing as the coldest the air gets is right at the evaporator (cold deck) where air moisture should condense & be drained to the outside. Once in the cabin the air will get warmer & be above its dew point.
Stay cool

DrainPond:
No fog or condensation on the glass inside or outside -- just on the outside on top of the roof (rear 1/3). Thinking there may be a piece of insulation missing in that section of roof? Thanks.

JasonMac:
Good thought - I will check filter. Thanks

Regards, Sunnyside

 

[GreenMtns]

DrainPond:
No fog or condensation on the glass inside or outside -- just on the outside on top of the roof (rear 1/3). Thinking there may be a piece of insulation missing in that section of roof? Thanks.

JasonMac:
Good thought - I will check filter. Thanks

Regards, Sunnyside

You might also want to check the drain hose. Some insects love small openings and build mud nests in them pugging them up solid.

Al

 

[sunnyside360]

You might also want to check the drain hose. Some insects love small openings and build mud nests in them pugging them up solid.

Al

Greeny:
Some water is dripping from the tubes when the A/C is running. But, I'll run a wire up into the tubes to make sure there are no partial blockages. Thanks.
Regards, Sunnyside

 

[sunnyside360]

Well, I removed and cleaned the cab air filter which did not seem to be very dirty, and I also checked the drain tubes for any blockages and there were none. In addition, I cleaned the unit in front of the radiator (evaporator or condenser?) and blew out with compressed air -- did not seem to be very dirty as I just cleaned it previous time I used it. I'm wondering if a piece of insulation or something may be missing under the roof where the air box is located causing the roof to chill down below the dew point and condensing water on top of the roof which is where the water is dripping down from.
Has anyone with 3X20 w/cab seen water forming and dripping from outside/top of the roof when the A/C is running on a very hot humid day?? If so, then this may be normal when humidity and dew point are very high.

 

[DrainPondDesign]

That does sound like an insulation problem, if we get a hot humid day before winter I'll check to see what our's does but it looks like our summer is about over.

 

[DrainPondDesign]

Forgot.

The evaporator (cold deck) is up there, if the cold air is leaking into the space between the shell & head liner it could cause the top to get colder than it should. Maybe one of those air duct hoses came loose or the plenum is leaking?

 

[sunnyside360]

Forgot.

The evaporator (cold deck) is up there, if the cold air is leaking into the space between the shell & head liner it could cause the top to get colder than it should. Maybe one of those air duct hoses came loose or the plenum is leaking?

DrainPond:
Good thought. Earlier this year there were a few 3X20 cab owners here on TBN that had an issue with the air box (or ducting) in the roof compartment which affected the cab heating. When I took delivery of my tractor in March 2007 I questioned the JD dealer about lack of heat as it seemed anemic. So maybe there is a leak in the ducting or air box which affects both heating and cooling. I would check the roof compartment myself if it is not too involved.