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.

 

[radman1]

I used my 3720 last night. About 92F, cloudy and extremely humid. I had condensation all over the top of the cab, water dripping down the front window and down the drain tubes in the back. I had condensation inside the cab windows as well and it difficult to see outside. I was frequently getting in and out of the cab, which let more moisture into the cold cab air. This probably cause the inside condensation. I suspect for the high humidity, this was probably ok. The cloudiness, also didn't let the windows get hot enough to evaporate the condensation off the windows. However, it was really nice an cold inside the cab.

 

[sunnyside360]

I used my 3720 last night. About 92F, cloudy and extremely humid. I had condensation all over the top of the cab, water dripping down the front window and down the drain tubes in the back. I had condensation inside the cab windows as well and it difficult to see outside. I was frequently getting in and out of the cab, which let more moisture into the cold cab air. This probably cause the inside condensation. I suspect for the high humidity, this was probably ok. The cloudiness, also didn't let the windows get hot enough to evaporate the condensation off the windows. However, it was really nice an cold inside the cab.

Thanks for your help. Your experience is identical to mine but you have given a better more detailed description. I did some mowing today in same weather conditions except the sun was shining (vs cloudy) and I did not have any water dripping down the front & rear windows but there was a slight amount of wetness on the outside rear portion of the roof shell. Evaporation from the sun may have a great deal to do with it.
With the blower on high, medium and low I noticed there was considerably less air coming out of the right rear most exhaust duct as compared to the others so the duct may be disconnected. Probably the only way to know for sure is to disassemble the roof compartment and check it out.

 

[minimax]

I have had as much as a 1/2 inch of ice built up on my 3720 roof on a hot day with the A/C running hard.

minimax

 

[sunnyside360]

I have had as much as a 1/2 inch of ice built up on my 3720 roof on a hot day with the A/C running hard.

minimax

WOW!! It sounds like your A/C works very well (or maybe there is a air leak in the air box/ducting in the roof compartment). I've never had ice buildup -- just a lot of condensation & water. I don't think this is normal as I've had larger farm tractors with A/C systems which did not do this.

Just curious, does your heating system work very well, eg, a lot of heat?? I ask because mine does not get very warm and am thinking there may be air leakage in the ducting or air box. Running the engine at rated RPM's does help with heat but I think it should be better. Again, I'm only comparing with other tractors I've had.

Sunnyside

 

[minimax]

Heat works good.

minimax

 

[Silver_Knight]

I know this is an old thread but does anyone know why my A/C on my 3720 would cool sometimes usually until it gets in the mid to high 80s and then the temp coming out of the vents will go as high as 80-88 degrees? When it is cooling it will be 60 degrees coming out of the vents.

I have cleaned the roof filter and washed out the fins on the unit in front of the radiator.

 

[radman1]

60 degrees coming out the vent is way to high. I don't see how your cab is cool at all. You should be able to stay cool in 100 degree heat. Cabs are like small green houses. I had to add refrigerant to mine last year (1 can) and then it did great. Just recently took my 3720 to dealer to have seal in the front axle repaired under warranty. I had them check the a/c because of what happened last year and it seem a little poorer on cooling this year. However, the poorer cooling could have been my imagination. They added a little refrigerant (1/2 can) but told me the air coming out the unit was already at 30 degrees!
I did have a problem with the heat/cooling when I bought the tractor new. The tractor engine would never warm up when 35-40 degrees. After multiple trips to different dealers, calling JD techs and regional rep, replacing the thermostat etc, they did find major air leaks in the corners of the cab/air box. Once they were sealed, it worked great.

 

[Nuru]

Radman, do you know how they foind those leaks?

 

[radman1]

Nuru

The site of the leaks were in the air box at the corners. The first dealer and area rep missed them. I was told, they are difficult to see and are partially hidden from sight. The heater/ac was bringing in too much outside air which was mixed with the air in the cab roof/box. A clue that tipped off the second dealer, was placing a sheet of suran wrap over the outside filter box where the air is suppose to come in. The wrap would not suck into the filter box like it was designed. They also noticed some dust in the corners or the air box at the areas of leakage. The corners were not sealed properly at the factory.

 

[Nuru]

Nuru

The site of the leaks were in the air box at the corners. The first dealer and area rep missed them. I was told, they are difficult to see and are partially hidden from sight. The heater/ac was bringing in too much outside air which was mixed with the air in the cab roof/box. A clue that tipped off the second dealer, was placing a sheet of suran wrap over the outside filter box where the air is suppose to come in. The wrap would not suck into the filter box like it was designed. They also noticed some dust in the corners or the air box at the areas of leakage. The corners were not sealed properly at the factory.

Wow that actually is a very good way to find a problem.

Thanks!