Help what is this?

The A/C is not "needed" for the defrosters, but does improve the performance of them. A/C is called "air conditioner" rather than "cooler" because it "conditions" the air; it "drys" it out, which speeds up the defrosting action. However, your defrosters will still work without A/C, just not quite as quickly.

darsben wrote:

Mr.Mark wrote:

ferndaleflyer wrote:
Freon has nothing to do with the defrosters----defrosters run off of the heater and the only relationship to the a/c is they both use the same blower usually--but not always.

Just curious, then why does the air-condition compressor come on when using the defroster? (on cars)

MM.

The compressor is used to dehumidify the air for defrosting both my cars and my class A gasser.
But what do I know

Autos use the compressor. A Lot of Motorhomes also, but not all. What I found curious was his statement about 2 blower motors. UNLESS you have an overhead defroster system the SAME motor operates all the dash AC systems. The Motorhomes I have worked on, the same blower motor operates the Defroster and dash system. Some motorhomes(Newmar's and some Monaco's were 2 ) had an overhead blower system separate from the dash AC/defroster system, to help blow air DOWN from the overhead. Doug

Mr.Mark wrote:

ferndaleflyer wrote:
Freon has nothing to do with the defrosters----defrosters run off of the heater and the only relationship to the a/c is they both use the same blower usually--but not always.

Just curious, then why does the air-condition compressor come on when using the defroster? (on cars)

MM.

The compressor is used to dehumidify the air for defrosting both my cars and my class A gasser.
But what do I know

ferndaleflyer wrote:
Freon has nothing to do with the defrosters----defrosters run off of the heater and the only relationship to the a/c is they both use the same blower usually--but not always.

Just curious, then why does the air-condition compressor come on when using the defroster? (on cars)

MM.

Freon has nothing to do with the defrosters----defrosters run off of the heater and the only relationship to the a/c is they both use the same blower usually--but not always.

Twomed wrote:
Probably a switch cut in by the coach builder to cut off the compressor when heavy load (hill climbing). Helps keep your cooling system from overheating because a/c takes a lot of power.

The answer to leak is that it is under pressure whether turned on or not.

As mentioned above a good a/c shop can replace the switch for you. Be sure they are capable of saving the coolant (Freon or whatever is in your system) and recharge without having you pay for a full re charge, assuming it still gets cold.

This is one of those longer you wait the more it might cost things. Not crucial if you don't run the a/c, but could get expensive in a hurry if you do. :) :)

NO RV chassis(Gas or Diesel class A) has a system that cuts out the compressor under heavy engine load. The switch pictured is a Pressure switch and since it has 4 wires it does 2 things. IF the pressure drops(coolant leak) it cuts out the compressor, and it also activates the Condensor cooling fan. Doug

reddfox77 wrote:
So what is a binary switch for?

A binary switch is one that is either OFF or ON.

A Trinary switch has ON/OFF/ON but the two on's are different

And then life gets to be fun.. I have one switch with like 120 positions..Not sure centurduodeka perhaps I do not know.

(That's a lot of positions)

Most of these switchs are can be changed without discharging system as they are on a schader valve. good luck dave

What year and chassis is your MH? Is the cooling system an Evans? In the upper L/H top of your picture should be a black plastic box that should tell you the system?

You don't want all the freon to leak out and stay that way. The damage will eventually get much more expensive regardless of use. I would get it fixed ASAP.