Skip to main content ↑ ↓
Topic: U280 engine AC switch not Blue (Read 567 times) previous topic - next topic

U280 engine AC switch not Blue

Hello, thanks for your help in advance.. b^.^d

Picked up camper from last trip.

82 degrees in FL

Turned on AC which worked last month
1. No blue indicator light, when turned on
2. Interior fan blows
3. Compressor cycles
4. Condenser fans don't blow

A. Is there a fuze for the fans? Where?
B. Expansion valve issue? Can these be replaced?

78 degree air out of vents

I understand a little...

Re: U280 engine AC switch not Blue

Reply #1 –
At least on the 1993 U240, there is a relay that power the fan.  Located on the driver's side in front-- open the "door" below the windshield to access it.

Check for power IN and OUT when dash A/C on and cooling (when fan should be running).

Re: U280 engine AC switch not Blue

Reply #2 –
Brett

On the firewall? With the wire connections?

Is it grey?

Re: U280 engine AC switch not Blue

Reply #4 –
They plug into grey box..
Fed by block to the left... 12v

Where do you want me to check 12v? Next post is picture

Re: U280 engine AC switch not Blue

Reply #5 –
Here is picture

Re: U280 engine AC switch not Blue

Reply #6 –
Sorry, don't have a wiring diagram for your model.

But, there will be one 12 VDC positive into it when dash A/C is on (from fuse box under dash lid).  Then should be 12 VDC positive out to the fans should be one (likely on a thermo or pressure switch triggered by high temperature or PSI).

A wiring diagram for your coach should give you the details.

Re: U280 engine AC switch not Blue

Reply #7 –
John
That pic is of your fan RELAY. It is controlled by the dash controls, low pressure switch and high pressure switch If it's like our 95. You can jump the relay out to test the fans to make sure they are good. (Probably are) You may also run a 12v wire straight to the relay to bypass the controls to verify the relay is good.

Might just try tapping on the relay with a screwdriver handle when the AC is on to see if the relay is stuck.

Re: U280 engine AC switch not Blue

Reply #8 –
12v works to fans
Found no fuze

Where is dash breaker or fuze?

Re: U280 engine AC switch not Blue

Reply #9 –
Quote from: fouroureye –

12v works to fans

Found no fuze

Where is dash breaker or fuze?

Not sure what you mean by "12v works to fans"
I wouldn't be too concerned about the Blue light on the push button, mine doesnt light either and the AC works fine. If the compressor cycles then the blue button is on.

the "box" to the left of the "grey" relay is your 12v breaker. Both terminals on it should have 12v to ground. One of the two large wires to this relay (orange?) comes from the breaker and the other large wire should go to the fans. The small yellow wire should energize the relay when the system calls for condenser fans to run ( condenser at set temp or pressure) the white wire should be connected to a good ground.

Your system is slightly different than mine so a wiring diagram of yours would help.

Re: U280 engine AC switch not Blue

Reply #10 –
Justin, thanks.. I will check. OK on blue light..

The terminals do have 12v..

I thought Brett said dash breaker-fuze? It's not in the 2 labled blocks

Re: U280 engine AC switch not Blue

Reply #11 –
If you can jumper 12v to the yellow wire the relay should energize unless its defective or has a bad ground connection. (white wire)

If it "pulls in" then you should have 12v to your fans, if not ........... relay defective.

Last year I replaced my relay and both fan motors, one quit running and the other ran slow even with a new relay so this prompted their replacement.
New fan motors move much more air now.

Re: U280 engine AC switch not Blue

Reply #12 –
The fuse supplying the dash A/C (at least on the 1993 U240) is in the block of fuses accessed by raising the dashboard.  Driver's side and labeled.

25 amp according to my wiring diagram and on one of the "ignition hot" blocks.