Crisp air issues on T1N 4x4

[Chikara]

Hi guys having major issues with my pcb board overheating and causing all sorts of problems with the ac and fan controls

 

[Eric Experience]

Chikara.
I have wasted a lot of time on these ridiculous air con units, the best idea is to pull the whole system out, they are just to much trouble and weight. Eric.

 

[Midwestdrifter]

Eric has dislike of AC which borders on religious in it's strength. To the point he disables it in his vehicles.

Can you identify which components are getting hot? If possible get the board out so we can see the back side.

 

[jaahn]

Hi Chikara
If you want some suggestions then you will need to be more detailed in what is happening and the problems.
What year and model is your van. There were running changes year to year.
Is your van an ex ambo or other ?
Has the air con been modified ?
Generally there should be nothing on the board that should heat up so there could be some failure or a short. But you have the circuit diagram so a good clear picture of that would show what it actually controls.
Jaahn
PS I have put some information currently in another thread also.

 

[Sockeye770]

My company wasted lots of money on the rear aircon in our 2001 516.
Gave up on trying to fix it before finding this forum.

 

[Eric Experience]

Yes I dislike the roof top air con units but its not religion it is an understanding of how they work. If you take the heat out of the van body and transfer it to engine compartment ,which is what the ridiculous units do, you end up with the vehicle sitting in a pool of very hot air, this hot air warms up the body which sends more hot air to the engine compartment, this keeps going until the system can not handle any more heat and the interior warms up. The factory air con units pump the hot air out above the roof and work in a reasonable way. Even so we don't sit or sleep in the back with the engine running so still can not justify carrying the extra weight. In my vehicles I use a large forward facing air scoop to get bulk cool air inside the body this means that when you pull up to set up for the evening the vehicle is cool, works a treat. Because the vehicle is well below GVM we can carry more fuel or water or toys if we want. Eric.

 

[Chikara]

Hi guys thanks for the comments the ac works fine until the pcb board gets to hot and the shorts out the controls then which then makes the van fan controls and thermo fans stay on all the time until I disconnect the battery and the crisp air resets itself.
I have attached pics of the board .

 

[Chikara]

My van is a 2004 316 cdi 4x4 navy ambulance put into service in 2005

 

[jaahn]

Hi Chikara
Thanks for providing the extra information. Now more questions from me others may know something more.
When you say " until the pcb board gets too hot ", have you noticed some items get hot to touch or is that just a general statement, that after a while using it the problem starts.
I ask this because there are some electronic active components on the board at the top and one could be failing and electronics technicians do use a freeze spray to test items for heat failure. Looking at the board in the picture there does not seem to be obvious hot spots but hard to say from my computer keyboard. But you can go over the items visually with a magnifying glass and all the solder joints to look for poor joints. Do you know any good electronic tecko that would do this for you ?
The dash switch unit should also be looked at for problems at the same time as it communicates the commands to the control board.
Jaahn

 

[Eric Experience]

Chikara.
There should not be high currents flowing in the cct board, one possibility is you could have an earth missing on some component and so the component is finding an earth through the cct board. To test this theory measure the negative wires coming back from the ac to see if they have voltage on them. Eric.

 

[Perce]

Yes I dislike the roof top air con units but its not religion it is an understanding of how they work. If you take the heat out of the van body and transfer it to engine compartment ,which is what the ridiculous units do, you end up with the vehicle sitting in a pool of very hot air, this hot air warms up the body which sends more hot air to the engine compartment, this keeps going until the system can not handle any more heat and the interior warms up. The factory air con units pump the hot air out above the roof and work in a reasonable way. Even so we don't sit or sleep in the back with the engine running so still can not justify carrying the extra weight. In my vehicles I use a large forward facing air scoop to get bulk cool air inside the body this means that when you pull up to set up for the evening the vehicle is cool, works a treat. Because the vehicle is well below GVM we can carry more fuel or water or toys if we want. Eric.

G’day Eric, can you elaborate on the forward facing air scoop you mention please.
Regards Perce.

 

[jaahn]

Hi
My thoughts on air conditioners in my Sprinter bus. If we did not have an air conditioner to use in hot weather I would not be driving a Sprinter. We live in Australia !!! Sitting in the high seating position behind the huge windscreen that extends to high above us, and close to the sides, the heat input is very very high particularly when the sun is towards the front. Having an air scoop would not suit me. I have put a reflective band across the top of the windscreen and the top of side window windshields to help prevent the sun coming in. And the bus is white with tinted rear windows .

We have in the past had the a/c fail in very hot weather and had to continue on with wet towels and improvised air scoops. IT WAS HELL. Not to mention it just dries out your skin so after a couple of hours you are like a dried prune. Sorry not for us. We do not usually use the rear unit but as we have some seats there will do so if there are others there.

Also a comment on the condenser in my bus a/c system. It is not mounted in front of the radiator but has a separate unit mounted low on the side behind the driver blowing out sideways through a grill. It has three 12V fans which it can switch on automatically as necessary. So it does not add the a/c heat to the engine compartment. The compressor is not a Mercedes unit either.
Jaahn

 

[Eric Experience]

Jaahn.
I also live in Australia And find the air scoop works fine, we do get a bit hot stuck in a traffic jam but mostly comfortable, Your set up sounds a lot better than the ones I am complaining about. Eric.

 

[Eric Experience]

Perce.
I have 3 versions of the scoop, the best is mounted on the hole that was the factory air, the scoop is adjustable from the drivers seat, fully open it is 200 by 400 closing down to zero. Being that far back is a problem on dusty roads as some dust from the front wheels does get up there. not enough to be a problem but annoying. The air flows through a fine mesh and the scoop is lined with carpet to reduce noise. If I get a chance to build another one it will be similar but with the air intake over the windscreen. Eric.

 

[kappy5003]

Yes I dislike the roof top air con units but its not religion it is an understanding of how they work. If you take the heat out of the van body and transfer it to engine compartment ,which is what the ridiculous units do, you end up with the vehicle sitting in a pool of very hot air, this hot air warms up the body which sends more hot air to the engine compartment, this keeps going until the system can not handle any more heat and the interior warms up. The factory air con units pump the hot air out above the roof and work in a reasonable way. Even so we don't sit or sleep in the back with the engine running so still can not justify carrying the extra weight. In my vehicles I use a large forward facing air scoop to get bulk cool air inside the body this means that when you pull up to set up for the evening the vehicle is cool, works a treat. Because the vehicle is well below GVM we can carry more fuel or water or toys if we want. Eric.

Eric, I still have the rear A/C intact, although the previous owner disconnected it and I don't know how, planned visiting establishment to discover what's missing.
Also considered removing it and making more roof space, but need some guidance on removing 2nd compressor, pipes and roof unit.

 

[Eric Experience]

Kappy.
It is pretty straight forward removing the compressor and pipes, to get the rear unit of just cut it off about 100 mm above the gutter then with the main part out of the way go around again cutting closer to the gutter but watch you do not cut the roof. find the screws and remove then cut the silastic out with a wood chisel. Eric.

 

[kappy5003]

does the second compressor run off its own belt or is it shared, may try and save for A/c in my MH.

 

[Eric Experience]

kappy.
Yes it has a separate belt, what sort of belt do you have on the motor home? unlikely to be compatible. Eric.

 

[kappy5003]

I had a rush of something to the head, fitting the compressor on the bus and mount the cooling bit on the roof over a vent.

Maybe more trouble that its worth.

 

[waybow]

Hi
I have a 2001 ex ambo 316 I with rear aircon. The PCB board is identical to the ones Chikara had images of above. My issue is a loss of connectivity for the compressor wire. I am at a loss of what to test on the board to see which component/relay has failed. Think it is one of the FRA2C-S1 7pin relays but I have no idea how to test them ? Any assistance would be appreciated
Thanks
Wayne