A/C Question

[Greenleaf]

Guys, my compressor will engage and operate for 25 seconds, disengage for 10 and repeat that cycle. This is NOT how the compressor operates in my other vehicles. They run for long periods of time w/out disengaging... ... ... ... . (???????????) I just had the system charged to the proper fill level with 134a by a reputable shop. They say everything is go for launch.



Whadda ya think?



Scott

 

[dusthomps]

I believe my 91 is the same while idling. I would say during normal driving, it will run continuously.





Dustin

 

[MMiller]

Every A/C system I know about has several things that control the clutch cycling. A high pressure switch, low pressure switch, a sensor in the evaporator. If the evaporator gets too cold the sensor will shut off the compressor to prevent the evaporator from freezing up. Then when the temp comes back up then the clutch will kick back in. If the pressure in the a/c system gets too high on the high side it will kick out, also if the low gets too low or into a vaccumn then the compressor kicks out to prevent more damage.



Couple things to look at. Is your engine fan clutch in good shape. If the condensor does not have enough air flow over it, the a/c system will not work right, and the clutch will cycle. Is your truck leaving a puddle under the cab on the right front. If not get the drain hose found and dig the little caterpillar nest out of it, so you feet and floorpans don't get wet. If you live in a real dry region then this may not apply. Here in iowa on a hot HUMID day a/c systems pump out gallons of water. I have to be careful with my service truck. It could get stuck in a field after the truck has run all day while I am working with the boom and on board air, because of the mud under the truck.



Does your truck have cold air comming out of the vents? Are you comfortable in the cab on a hot day? Get a thermometer and stick it in the vents and see the vent temp. Ususally I can get down to low 30 Degrees F with most 134 A/C systems. It may be higher on yours being the system is r12 converted to r134a.



As long as you are "cool" in the cab, and the temp is not going up and down, everything is working correctly. The clutch in and out is how the a/c system regulates it self.



Are you satisfied with the temp in the cab, versus the r12? My truck a/c is acting up, and I know it will be $$$$ for r12 repair, but if I can change it to R134a then I have all the stuff to make it work. Just wondering.



Michael

 

[Blue Ox1]

When you say proper level is it 75 percent of the original volume or is it the same amount of r12?134 runs at a higher pressure so when switching to 134 from r12 you need to add approx 75-80 percent of original fill volume. Only reason I know this is I changed a ford ranger over to 134 and overfilled and had a pretty similar condition to your compressor cycling alot

Joe

 

[Greenleaf]

I have installed a temp guage in a vent to monitor the a/c function. It operates about 50° but will reach 47° on a good day. I'm satisfied with that as I've been told this new stuff won't cool well in a conversion. The wifes car and the old Ford will reach 40°, which is too cold anyways to be comfortable.



The condenser is new and fan works well. The a/c shop checked and monitored the pressures in the system... all seems ok. I have also checked the pressure of the low side and it's exactly where it should be.



Sometimes I'll have a pool of water and sometimes not. When I bought the truck, the water drain was plugged up with oak leaves. My floor got wet then.



Scott

 

[Forrest Nearing]

Scott,



do a search on the net for "Duracool"



it mimics R12 and actually cools better... it's compatable w/ R12 or 134. non-corrosive. has a higher ignition temperature than 134, etc.



it's the only way to fly IMHO. I've been using it for over 5yrs now and I LOVE the stuff.



I run it in all my R12 equipped vehicles, and I also spike my 134 vehicles w/ it. (if you run it straight in a 134, it'll get so cold it'll freeze over the evap core)



Forrest



PS, in TX there's no such thing as "too cold" when it comes to AC!!!

 

[Greenleaf]

Thanks Forrest, for the words of wisdom... ... ... My wife can't tolerate the cab to be too awful cold. She will carry a blanket in the cab when we travel a ways. I like it a bit on the chilly side. Have you seen the latest commercial for NAPA with the race car guys inside a car... . at the beach



-S

 

[Forrest Nearing]

I haven't seen it yet, I'll have to keep an eye out.



I like it when the AC is so cold it hurts your skin.

 

[RDHamill]

I just switched mine over to Red Tek R12a, from the stock R134a, air form dash is now almost 20 F cooler.

I also switched my car from Duracool R12a to Red Tek R12a, it also got quite a bit cooler.

Also noticed that the high side presure dropped about 100lbs.



I'd offer this advice to anyone converting from OE gas to anything else... install the new gas with guages, and watch the low side presure, I've seen folks use charts to base the quantity of new gas to be installed, this seldom is accurate enough.

As mentioned above by some of the other guys, some of the probelms discribed some as a result of either just a little to much or to little.

Good luck and stay cool

 

[Forrest Nearing]

what I need is an adjustable low pressure switch... when I ran straight Duracool in my '97, if I ran it at a high enough pressure to keep the compressor from cycling at speed, it turned the evap core into a solid block of ice! LOL!



I'm currently running 134 with about 15-20% Duracool. It's COLD! hurts your skin. I'm gonna get a thermometer on it later this weekend.



Forrest

 

[Greenleaf]

I should do something!!!

It takes forever to cool off the cab with the 134a when it's only blowing out 50° air!!! Not bad after a 1/2 hour, but when inside cab temps are 100°+ ... ... ... .



I'll be in southern FL for a week... ..... in August :{ :{ :{



Scott

 

[MRickard]

Mine cycles around here and there too. Have not had the time yet to get into it and set it up right. I run them with the compressor always on, and fix the expantion valve to put out a little more. No ice probs out here in the west as it is dry, but factory is set for everywhere. What is nice is staged evaporators so you can crank out cold air - turn the cab into a freezer. Feels good.

 

[Forrest Nearing]

staged evaporators? dual cores?



explain... I want a friggin' meat locker for a cab!

 

[tugboatphil]

Scott,



When I'm on the road, I make an effort to park with the front facing the afternoon sun. I put up one of those silver reflective shades EVERY time I get out, and since I have the upper window rain shields, I leave the window cracked 1/2". It makes a big difference in cab temp when I get back. The large window screen is too big, so I cut it to fit.



As to the wife bringing a blanket... . when Sandy makes a trip with me, the amount of blankets, pillows and other foo-foo items takes up just about the entire extended part of the cab!!

 

[NIsaacs]

This probably does't relate to on/off cycle of AC compressor, but may relate to warm air if AC checks out, is the hot water on/off valve to heater. If it malfunctions the hot water will negate(is this a word) the AC air.

 

[RDHamill]

Negate, ya that's gotta be a word, but if it ain't, it's yours now.



the other thing that could effect cab air temp would be the blend door in the dash, which mixes the amount of a/c air with outside air.

good luck

 

[CKnoop]

I was all set to convert my 84 to 134a when I saw a ac post here and Forest N recomended Duracool I checked out there website and ordered some Oo. I am a happy camper cold ac. I didn't like the idea that 134a woudn't cool as well as r12 in my system but the Duracool works great I can hang hams in the back now first time the ac has worked since I had the truck

 

[tugboatphil]

Originally posted by CKnoop

... I can hang hams in the back now

I hope you're not running the smoker while you're driving!!!