Diff Lock / 4wd

[GlueGuy]

What RPM stated is true. The idea is to "dry out" the air used for defrost. Also tends to cool it a bit, so I don't generally leave it on too long if it's real cold out./w3tcompact/icons/smile.gif Luckily, it never gets too cold around here. /w3tcompact/icons/smile.gif

The GlueGuy

 

[Bird]

Scruffy, I always understood the purpose of the a/c compressor coming on with the defroster was twofold; one to condense moisture, as mentioned by RPM, and the other to run the compressor, but I thought that did circulate the refrigerant through the system. Is that not true? Are there parts of the system that don't get circulated without resorting to using the cooling system? I'm not much of a refrigeration mechanic; just got back from town to buy a new freezer because ours died yesterday./w3tcompact/icons/frown.gif

Bird

 

[scruffy]

Bird, RPM & GlueGuy may well have corrected me on that point. I haven't kept up on it for years (21 to correct) so the properties now involved may well be as they say. I would, and do, still run mine occasionally so that the circulation is not left to doubt. I had a 72 Chev 1/2 ton that never had the air serviced over its 23+ years that I had it...worked fine. My 95 Ram is still or should I say was still working fine when it got wrecked...damper and other items replaced, and it now needs to be charged...as it doesn't get near as cold as it used to. Who knows..more than likely something done at the body shop, or should I say not correctly done at the bodyshop. You know these young pups, got more recent data than us ol' farts!

 

[RPM]

Bird - I wouldn't worry about not fixing the freezer - there's almost no way they can be maintained at home. They mostly have sealed components which are very hard to source as an individual. Anyway ... for the low cost of replacement (and hassle free operation for the next 10 years) I'd rather spend that time on my new BX.

BTW - the compressor referred to was the refrigerant compressor. The air-flow is provided by the normal vent-fan which blows air over one of the A/C systems 2 heat exchangers (one cools the air in the vent system, the other 'pumps' the excess heat out under the hood).

It's as the warm, moist air passes over this cold heat exchanger that the condensation takes place - thus drying it. When the air reaches the windshield it's dry and there's no moisture left to condense on the cold glass.

So, all parts of the system are working ... I actually don't like this when it comes on automatically with the defrost setting. Seems a waste of gas when you have to run the defroster on a cold but dry day.

FYI - the new ozone-friendly refrigerants are not as good at their job as freon was. This is one of the reasons why people seem to need a recharge more often. Another is probably because they are running their A/C systems all winter when they defrost their windshields!!

I have to say that in the nice weather we had in PA on Tuesday I was enjoying the ventilation system on my BX to the full ...

 

[MJB]

My day job is as an engineer for Carrier Corporation (worlds largest HVAC manufacturer) so I know quite a bit about air conditioning. Wasn't this thread supposed to be about Diff Locks and 4wd?/w3tcompact/icons/smile.gif Refrigerants R-12, R-22, R-134A, etc are very poor lubricants, they are actually solvents. Any AC system with a compressor has oil in it (usually mineral oil or Alkylbenzene for R-12 and Polyalkylglycol or Polyolester for R-134A) to lubricate the compressor parts. It is good to operate the compressor once in a while to circulate the oil around the system and get it back into the compressor where it belongs, because the oil will migrate out of the compressor somewhat when not in use. The problem with doing this on automobiles in the winter time is that the compressor clutch is controlled by a low pressure switch on the suction side of the compressor. If it is too cold outside the saturation pressure of the refrigerant will be low enough that the pressure switch will not close (and the compressor will not run) even though you have the switch on the dash set to AC or defrost. You will have to pick relatively warm days in the winter to ensure that the compressor actually runs. It is true that the new refrigerants (R-134A etc) are not as efficient at heat transfer as R-12. This is not a problem, however, if the system is designed to use R-134A. The condenser coil in front of the radiator needs to be larger for R-134A than R-12 in order to have the same efficiency. Any AC system only needs to be recharged if there is a leak. Refrigerants never "wear out".

 

[RobertN]

Ya Bird,
If the air conditioning becomes disabled for whatever reason, the defrost doesn't work worth a hoot. I've seen people disconnect the air system, and then they can't defrost. The defrost system is different for a vehicle without air(not sure of details though...)

RobertN in Shingle Springs Calif

 

[RobS]

Re: Diff Lock/waaay off topic

Hey MJB, are you at the main Carrier plant there in Syracuse by Carrier circle? I used to stay in a hotel right there when I visited a molder we use in Canastota. That's a real pretty part of the country. We've contemplated vacationing in the finger lakes area and may do that one of these years. My wife will draw the line at my bringing the tractor along though /w3tcompact/icons/smile.gif

 

[MJB]

Re: Diff Lock/waaay off topic

RobS,
I sure am. Building TR-4 to be exact. You are right about it being pretty country (at least for April through November, it is real ugly for the rest of the year/w3tcompact/icons/laugh.gif) The fall colors in the Adirondak mountains is something that just has to be seen to be believed.

 

[RobS]

Re: Diff Lock/waaay off topic

OK MJB, here's our chance to bring this thread back on topic...

Isn't there a New Process Gear (now New Venture Gear?) plant just east of Syracuse on the Thruway? Isn't that where they make transfer cases with or without center differentials?

OK it's weak, but a good way to close the thread /w3tcompact/icons/smile.gif

 

[MJB]

Re: Diff Lock/waaay off topic

Yes there is. I drive right past it everyday on the way to work. It is a huge factory and I can tell you from experience that you don't want to even try to drive past there when first shift lets out./w3tcompact/icons/shocked.gif I don't think that they make anything for tractors though.