BostonETC97 Posted August 22, 2006 Report Share Posted August 22, 2006 As the summer progresses, I feel like the a/c has gone from incredibly cold to "coolish." I can't figure out what I'm overlooking. The pressure checks at 35-45 on the lowside to 250-280ish on the high end. The compressor cycles as it should (runs for a good 30-40 seconds, cycles off for 10 secs or so, and back on again), and doesn't make any strange noises. I had it replaced last summer, along with a new orifice tube. On the highway it gets real cold, and it seems to get colder while driving up or down an incline. At idle or in traffic it's still "cool," but not the cold I remember. In the past if I had it set on 68, it'd be perfect, and 65 would be cold. I'd never turn it to 60, as it'd freeze me out of the car. Lately Its on 65, and 60 on a hot day. Any ideas where I should start poking? Link to comment Share on other sites More sharing options...
Ranger Posted August 22, 2006 Report Share Posted August 22, 2006 Are the cooling fans working when the A/C is on? Is the condensor clear of bugs? Link to comment Share on other sites More sharing options...
BostonETC97 Posted August 22, 2006 Author Report Share Posted August 22, 2006 The two fans behind the radiator are running well. Never checked the condenser. How do I clean it out? (And where is it? ) I've been trying to figure out all the "stuff" going on near the radiator. There seems to be a "mini radiator" on the driver's side infront of the main radiator, my guess is that it's for tranny fluid. Then there are lines going into each end of the main radiator, which I've assumed are for engine oil cooling. If anybody could clarify this for me, you'd be my hero! Link to comment Share on other sites More sharing options...
Ranger Posted August 22, 2006 Report Share Posted August 22, 2006 The condensor is what you are looking at when you look through the grill (where the bugs collect). Clean it out with compressed air or a garden hose. The radiator is behind that. The lines to the radiator side tanks are for oil cooling (passenger side) and trans cooler (drivers side). The small one in front may be for P/S fluid. Link to comment Share on other sites More sharing options...
WarrenJ Posted August 23, 2006 Report Share Posted August 23, 2006 When I bought "baby," I had all the fluids drained and replaced (NOTE: no "flushing"). Also, a new battery went in without regard to the condition of the "original" battery. I had the A/C evacuated and recharged due to a "LOW REFRIG" warning. Yep, I'm anal. That said, however, I have to say I'm not entirely impressed with baby's A/C perormance. Sure, it's good, but it doesn't even begin to measure up to the performance of my frigid '70 Cutlass Supreme or '71 Mark III. Or even the '83 Mark VI. I'm not a big fan of 134a. We're a generation apart, so I'm not sure comparing notes among our models is a good idea. You pointed out, however, that it was better in the past. In that case, I'd go for it. Let's first get back to "normal" and take it from there. Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
BostonETC97 Posted August 23, 2006 Author Report Share Posted August 23, 2006 The coldest air I've ever experienced was in a late 70's diesel mercedes (300-D?) sedan. So cold that the air looked like it was "smoking" out of the vents. Besides that, my first car, an '88 Cutlass Supreme SL coupe also had the "icy" air. I miss R-12. Overall, I can't complain too much about the R-132 system in the eldo. It does eventually get cold, and works alot better than many other 132 systems I have been around. I might just be conditioned to the system, and with the hot weather around here lately, I'm just whining more than I should. Pretty soon I'll be on here asking what snow tires are best, and how to free a 4000 pound cadillac from a 5 foot snowdrift. Link to comment Share on other sites More sharing options...
KHE Posted August 23, 2006 Report Share Posted August 23, 2006 Pressures are a good troubleshooting tool but they don't always tell the whole story. The only positive way to determine if the system has the proper charge is to have it evacuated and weigh it. R-134a systems (not R-12 systems that have been retrofitted to R134a) should perform as well as the old R-12 systems if everything is in proper working order. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KevinW Posted August 23, 2006 Report Share Posted August 23, 2006 The compressor should not cycle every 30-40 seconds in typical summer ambient temperatures, with the engine operating at idle speed and the HVAC blower on high. Do you observe a noticeable increase in blower induction noise when 'Recirculate' mode is activated? Recirculating interior air reduces load on the system, contributing to lower vent temperatures. The loss of this function might explain a decrease in performance, everything else being equal. Sounds like there was something altered or broken on that old Benz. Nearly every car has some sort of control mechanism to prevent evaporator freeze-ups. Assuming a 10 F differential (evaporator under high load), the coldest practical vent temperature would be 42 F to avoid ice build-up. I have seen temperatures as low as 25 F from an R-134a system, but it was not intended to work this way, and required a defrost cycle every 15 minutes (no air recirculation). Assessing temperature using the back of one's hand is too subjective; a thermocouple or thermistor based measuring instrument, or even a bulb-type thermometer would assist in the diagnosis, as long as the operating conditions are recorded. ___________________________________________________ Link to comment Share on other sites More sharing options...
BostonETC97 Posted August 23, 2006 Author Report Share Posted August 23, 2006 The recirc feature is functioning, and on the extremely humid days really cools the car much faster. Perhaps I should just make it a point to leave it on recirc when I'm running the a/c. When the HVAC is at Auto-60 (lowest), does it automatically set the recirculator door? I'll check the exact timing on the compressor cycles tomorrow. I also never got around to cleaning the evaporator/radiator area tonight. I don't recall it being "stuffed" with debris, but I'm sure 99% of the debris in the fins isn't visible anyway. What's the best method for cleaning the fins without inflicting damage? Will high-pressure water stream from a hose and nozzle be ok? Would a pre-soak with simplegreen be a good idea? Link to comment Share on other sites More sharing options...
Ranger Posted August 23, 2006 Report Share Posted August 23, 2006 What's the best method for cleaning the fins without inflicting damage? Will high-pressure water stream from a hose and nozzle be ok? I have always used compressed air first, then flush with a garden hose, but not so high of a pressure as to bend the fins. Link to comment Share on other sites More sharing options...
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