Hi everyone,
ok so when i start up the truck in the morning the ac work perfectly, blows nice and cold. id say about 10-15 minutes after im on the road, im rolling along at between 2000-3000 rpm and it starts to blow warm which really suck in Florida. but the thing is, if i downshift and keep it between 3 and 4 grand for a little while, the ac blows cold again. and so i go back and forth to keep the ac cold, lol. now i used one of the gauges that comes with those r134a cans and it said that the refrigerant was full (i think around 75-80psi, but im not too sure). so im not too sure if the gauge was wrong or if its something electrical.

also sometime the ac (whether blowing cold or warm) switches from the vent to the defrost. i looked through some of the post and they said something about a vacuum, but im still a little confused on how to take care of that.

any advice you all can throw my way would be just awesome.
thanks in advance.

 

How fast are you driving when it blows warm?

The vent doors are opened by vacuum motors. When there is a leak it will default back to defrost. You need to check your lines and the reservoir located under the air box.

 

ok cool, ill definitely be checking those out this weekend.

but as far as the air, its blown warm at slow speeds, on the highway, you name it.

 

It should never blow warm on the highway. I was thinking your fan clutch was bad. Im leaning toward electrical issue now. FYI the ac will cut out on heavy throttle. So stay below 3k when it gets warm.

When it gets warm is the compressor running?

 

Hmm. I guess i dont really recall if it happens on the highway or not.

Now that ya mention it, i recently replace a fan motor on a camry due to the ac blowing warm and it worked like a charm. Still, i didnt even think to check the fan clutch on the truck.

Ill also check to see if the compressor runs when it blows warm.

 

ok so i checked the truck and the fan is working just fine.

i also checked the compressor and it does not run when the air is blowing warm.

could that mean a compressor problem or low refrigerant?

 

First off what year is your truck? If you are a 94 or newer you are 134A refrigerant, you can buy a recharge kit with hose and gauge for about $20.00. Try one can and if that works you may have a small leak that is only present when the system is running. If it works problem solved if the problem returns put a can dye in and look for the wet spot. Chances are you have a bad o-ring on one of the hoses they can dry out and leak overtime.

 

low oil in the a/c sys?

 

You said you have 75-80 psi in the system. I was hoping was a wrong value.


The low side should be between 20 and 30 psi when the ac is running.

If the compressor was dying it would make a terrible grinding noise.

Verify your low side pressure to determine if the system is correctly charged.

 

yeah your definitely right Blhde, it does not blow warm on the highway. i guess i got it confused because it blew warm when i was stuck in traffic.

when i get home i'll recheck the pressure with the can gauge just to verify.
does that gauge measure the whole system or just the low side?

oh an thanks again for the help everyone, im confident ill have this all sorted out pretty soon

 

the gauge only measures the low side. you shouldent mess with the high pressure side.

 

Im not sure if you tested the radiator fan. With the truck hot and offf, try and spin the fan by hand. It should not be easy to turn or turn at all. Another way is too open the hood and with the truck running rev up the engine. The fan is very loud when its engaged it should move a lot of air.

Im really betting you need a new fan clutch. Now the efan mod is about the same price as the clutch. It will give you colder ac when your not moving, say traffic.

 

i rechecked and the low side pressure is not around 70 psi, my mistake.
its actually it between 35-40 psi.

tomorrow ill test the radiator fan.

 

So as long as your moving the a/c blows cold right?

 

a ranger is an orifice tube system is it not??? i think FOT specs are 28-48psi or somethin more like that.. and it should go up when the compressor is running and go back down when it isnt.

 

actually you're half right, it blows cold when im moving at above 3000 rpm. anything below that and it blows warm.

ok thanks, ill check that when i test the radiator fan

 

i tried to spin the fan by hand after driving it for 30 mins on the highway. it spun very easily by hand. so what do ya think, new fan clutch?

 

Did you rev it up to see if it moved air?

Im willing to bet its bad. Again the efan mod is about the price of a new clutch. Unless a member here is willing to sell you theirs after they did the efan mod.

 

the fan clutch was definitely bad so im glad i replaced it, but the bad news is that the air still blows warm at lower rpm. right after i replaced the fan clutch it blew warm less frequently but now its blowing warm just as much as before. is there anything else that i could check or anything else you guys think it could be?

 

Try rinsing out your condenser and radiator with a garden hose.

You want water flushing it not pressure pushing stuff out.