Speedtoys

Makes sense..but when I do turn on the front...its instant 'swampy humid' feeling..so that might be what youre talking about.

The limit may be in the systems ability to get RID of the absorbed heat at the condenser?

GeorgeM

Mine works great regardless, until the Freon leaks out.

I have been running the rear regularly based on some comments that said to exercise the rear as well to keep the seals pressurized.

But the question remains... if I don't use the rear, will I not lose Freon from my leaky rear evaporator?

I'll get it fixed eventually, but don't have time before SITM, and if the weather is anything like it is now, I'll need a/c.

WallyP

If the rear system leaks, it leaks whether it is used or not. The solenoid stops flow thru the rear system, but it sees static system pressure anytime that the system is not running. The leakage will be less while the evaporator is at lower pressure (with the compressor running, the evaporator is at suction pressure), but that won't make too much difference.

There is no easy way to isolate the rear system.

GeorgeM

Thanks Wally... that's what I was afraid of.

dr bob

Limit is the ability to pump heat out at the condenser.


If you are getting a humid blast on light-off, spend a lttle time verifying that the evap drain is clear. If it's blocked at all, you'll end up with residual moisture in the evaporator. Heat with sun, add a little time, and the little living organisms make the water quite fragrant.

You would normally notice the water condensed in the evaporator cooling your feet if the drain is blocked, but that's less of an issue in the drier areas. If you pour a LITTLE bit (few ounces) of water into the evap/heater box, you should notice it coming out the drain. Bottom of the drain is above the heat shield just forward of the catalytic converter bodies.

blandis

Dr. Bob, Wally, Sean and others went through your checklist. Thanks for the help. Has some freon in it, and rear would cool a bit. No go with the front.

Ended up being low on freon. Sean added some r12 this morning and is now cold. Had enough to keep compressor running but would not cool.

Has a leak that I will fix if its bad.

Speedtoys

Bob: My drain is clear, I can watch it drip with the A/C on..including the nice puddle after parking..goal is to clean out the fuzz from the coils today...that'll test it.

dr bob

Jeff--

Take some before/after pics. FWIW, the partially-obstructed evap unit changes airflow bit won't change measured temperature much. With limited heat-transfer capability, the evap temp will actually be lower. Sometimes it's cold enough to reset the freeze switch and cut off the compressor, since not enough hot air is being drawn through.

Speedtoys

*nods*

What if the shop put in the R12 weight of R134, and im overcharged? How does that change it all up?

dr bob

Risk of overpressure on the high side if/when you get caught in slow traffic and airflow through the condenser is low. It starts to be a serious challenge above 95º ambient, but can be an issue earlier if either of the engine cooling fans takes a vacation. Hence the recommendation for using the later GTS safety switch on converted cars.

Also- Too much refrigerant will limit the low-side temperatures. The compressor is sensitive to changes in discharge pressure, so having a higher pressure in the outlet will also limit how low the suction pressure can go. Low suction pressure equals colder evap temp capability. There are a few other considerations, but the temperature in the evaporator will never go lower than the corresponding [condensing] pressure.

Speedtoys

*nod*

Im having this checked on the 11th..someone I trust will do a free pull/test/refill on the system.


And..I expected afterwards to have -some- bubbles showing in the sight glass, as I read is typical with R134 swaps.

I have no bubbles, only fluid.

Speedtoys

Update Bob:

I put one of those little gauges that come with the R134 cans on the low side, fired up, and im showing about 30psi with front/rear on full recirc @ idle.

Speedtoys

Dr Bob: Project delayed.

http://www.homedepot.com/webapp/wcs/...7&marketID=109

Thats an internet only purchase..cant find it, or anything LIKE it..near me.

dr bob

Jeff--

Local SoCal stores have it in the water heater section, with the gas lines and other flex stuff needed with them. If you take your ad with the SKU to the service desk, they will walk you to the shelf.

For those playing along at home, the coil cleaner uses sodium metasilicate, a somewhat caustic degreaser, combined with some detergents and surfactants to help with dried-on dust coatings. If your evaporator is pretty well blocked with a dust/mud cake as many seem to be, it will take a few treatments and some mechanical agitation (read: soft brush and elbow flexing) to get it clean. The foaming coil cleaner is supposed to get into the fins and recesses to get at the layers of crud on the inner coils. Remember that the layer on the outside, the one you see, is just one of many layers of crud. The insides pack up too. Pull the blower resistor and use an inspection mirror to look deeper than that first layer. You'll be amazed at how much junk is stuck inside there.

Speedtoys

Ya..we tried that.

HD doesnt stock this where people are not expected to have A/C.

Or bar fridges, restaurant coolers, etc.