JD4720 Cab No air (heat) r coming from left side cab ports

[gimmodog]

JD must have decided that 2 blowers are better than one after mine was made. I do like the idea of 2 blowers as to maybe give better airflow. Mine does not cool that well on a very hot day. Now I wish mine had 2.

 

[kennyd]

JD must have decided that 2 blowers are better than one after mine was made. I do like the idea of 2 blowers as to maybe give better airflow. Mine does not cool that well on a very hot day. Now I wish mine had 2.

All the factory cab models should have two blowers.

 

[gimmodog]

All the factory cab models should have two blowers.

you made me curious if mine had 2 so I went out and looked. F3 for blower #1 and F4 for blower #2 so THANK YOU for correcting me. This summer the a/c and the radio didn't come on one day. Neither blower came on nor did the radio. F4 was blown, replaced it and radio and a/c both came on. Maybe I should check F3, it could be that the one side is not blowing and I haven't noticed.

 

[gimmodog]

All the factory cab models should have two blowers.

Since mine is a factory cab you made me curious if mine had 2 so I went out and looked. It does, F3 and F4 for blowers (didn't notice which was labeled 1 and 2 or left and right) so THANK YOU for correcting me. This summer the a/c and the radio didn't come on one day. Neither blower came on nor did the radio. F4 was blown, replaced it and radio and a/c both came on. I haven't looked at a schematic but apparently F4 will stop both blowers. Sorry for my misleading post earlier.

 

[orlo]

Ok. Brought it inside my heated shop. With a 25 AMP fuse I was able to get it to run on high - Sputtery at first.
Put back in a 20 and it'll run on high now no problem, but no air below high (Right side is fine). Ok, at this point
I'm thinking obstruction of the fan, etc. so I want to take the roof off. Does anyone know how to take
the roof off? I've removed 11 locknuts (All I can see - 3 each side, 3 in the front, and 2 in the rear) but other
articles I've seen state there are 13 (Of course they don't show where they are). Does anyone have instructions
for removing the roof so I can get at everything. I'm trying to pry from the sides but it seems awfully tight.

 

[gimmodog]

Sorry I can't help with the locknut locations. It sounds like a fan blower motor problem possibly a rusty shaft, bearing or internal electrical problem. I would think it would have some type of foam or something between mating surfaces that could be sticking.
I will look at mine and see what I find.

 

[gimmodog]

Mine has 3 on each side and front. Didn't take the cover off the back so not sure how many is there.

 

[kennyd]

I think a few are hidden by the amber marker lights, but it痴 been awhile since I致e taken mine off.

The tech manual details the procedure, sorry I can稚 post post and more details til later this evening.

 

[orlo]

I never would have thought, looking with a flashlight, but took the two rear marker lights off and well hidden were two more threadlock nuts.

Ok, took the motor out (after testing it on the roof), turns fairly freely with not a ton of signs of corrosion, etc. Note however there
was a 1/2" puddle under the motor - Does anyone else have this? I'm figuring condensate from after the motor gave out.

As mentioned, after I jarred the motor with 25amps It would run on high on a 20 amp fuse but no medium, or low.

After testing the problem is the resistor block (Similar to automotive designs) - Hi (no resistance) is fine, low, and medium are dead.

I'll price it out but I'm leery of just replacing the resistor block and I'll probably opt for the whole assembly.

I really need to get a service manual. Thought I had one but if I do I can't find it.


A related question is does anyone know the DIN size of the radio? While I have the roof off I may replace it with
something that has bluetooth.

Thanks,

John O

 

[kennyd]

I don’t know DIN sizes, but I replaced mine with a regular BT car stereo from Crutchfield, did the speakers too and now it sounds great in the cab! There are quite a few good threads on these if you search some, lots of others have done this too.