How much freon is in your system?

Like I said, you are having the exact symptoms I had in my '98 Durango. I bought a compressor, and all the HVAC lines, orifice, expansion valve, dryer, etc. I spent $1k and turns out even though my compressor was not cycling, my A/C was not even on the verge of cool. I figured it was not working properly. Just was low on freon.
I was just stickin' to the leather seats.

For like $40 you should be able to have a local A/C shop drain and refill your A/C with Freon and the proper amount of oil.


Merrick

 

It would only blow hot air though? I could understand being low on refrigerant if it was just a problem with the A/C alone but it blows hot air all the time no matter what the controls are set to.

I think i've got an A/C pressure gauge somewhere but it'll just be a matter of fishing it out of my toolbox in storage. I'll go ahead and test it just to be sure but I don't think this is an A/C related issue anymore.

 

The "blend door" actuator on your truck is electric, as it's difficult to get to I suggest you have a look at the control end first. The dash just pulls off and the sw mounting plate just unscrews. Try some contact cleaner first failing that a new or different control sw. Note that the earlier trucks use a boden cable system to control the blend door so if you go to a wrecker you'll need a newer truck to rob the sw from.

 

Check the freon level.

How is the a/c supposed to blow cold air if there isn't enough freon to compress and expand to get the law of thermodynamics to properly work?

Like I said, my durango had the same problem. Hot air at all times. I even plugged off the Heater lines running into the cab and it still blew hot air.


Here are to simple tests you can do right now.

1. Open Hood, and start truck, set a/c to max recirc and fan on high. now look under ther hood. Is the compressor turning? is it cycling on and off? Spinning for a few seconds then stopping?

If it isn't turning, or is cycling, then it might have a bad high side, or low side switch, but is probably low on freon.

If it is turning, move onto simple test two.

2. After the truck has been idling with a/c on for a few minutes, check to see if the condensor is hot. If the condensor is about the same temperature as the intercooler (Which is most likely kinda warm), you are low on freon. If it's freakin' hot then it has some freon (probably low, but the condensor can be burning hot and still not blow cold air), if it's just really really really warm (~175*), then your a/c is probably working fine and you need to proceed on towards vacuum leaks and blend door probblems.

Merrick

 

im seeing close to the same symptons out of my ac, when its hot outside (85+) mine will blow ice cold and then i smell a funny smell from the vents and it gets hot. it mainly does it when i have been cruising for a while on the interstate. if i let off the gas for a second and then get back into it the temp will cool back down. it doesnt happen all the time either, it has yet to happen in the morning when its still a decent temp outside. I just replaced the condenser because it was all beat up and when i did i vac'd down the system and then put in the appropriate amount of refrigerant. when it blows cold it blows really cold, its getting annoying though cause i know when its going to change(by the smell). any ideas?

 

moneytlks,

Sounds low on Freon to me. My truck does this. I have a pinhole leak and when it gets low on freon, it is either Ice cold (~35*) or mediocre (~65*). At idle, it's mediocre, and cruising it gets down to ~35*, for awhile maybe 10 or 15 minutes, depending on how low on freon the system is. Then the temperature drops down to about 30* and the fan gets louder and the air stops blowing. If I turn the A/C off but leave the fan speed on high, the temp will come up to about ~40* and the air will slowly start to blow again, along with a waterfall of water coming from under the truck.

When I have the system charged fully I do not encounter this problem. Some A/C mechanics like to overcharge the system for faster cooler air at startup, and others like to undercharge for colder air, but with the air not immediatly getting cold.

Low Freon will cause the system to freeze up, too much freon will not cool as well, but more predictably (less temp fluctuations between idle, and high RPM and no freeze ups).

Merrick

 

i know it has the proper amount of freon, we even weighed it this time with a scale (were using a new 60lb bottle). there is alot of water coming from the truck when idle or after i park. i just wish i could figure it out. my mechanic buddie thinks its some kind of temp switch thats going bad, because the change is so rapid from cold to hot-hot to cold. its really more of an annoyance than anything, especially when you have a date in the cab.

 

It could be the evaporator core is freezing up, Next time it does it see if there is water/condensation coming out the drain. If it's not coming out all the time and only comes out after you switch the compressor off leaving the fan on then it's freezing up. Have a look at the A/C line that runs along the top of the right front fender, that's the expansion tube. See if it's been kinked or flattened , the line also contains screens to trap any crud and could be partially blocked, you can't fix it only replace it. If you recharged the system by weight did you use a dialacharge or just scales? If you used scales it's not accurate and could be over charged. If you end up changing the expansion tube you should also replace the dryer at the same time and evacuate the system. If there are no leaks it should hold 28 inches of vacuum with the gauges closed and the pump off.

 

It isn't just the A/C though, even with the A/C off and the temp on the coldest setting it still blows blisteringly hot, there is no differential in temperature it is just always hot. Sometimes when I turn the A/C on it will blow cold for ~10 seconds, give or take, but then it just gets hot again.

I can hear the compressor kick on when the A/C is on, I haven't physically watched it kick on but it is working. Even if there was zero freon in the entire system I would assume it would still blow cooler air if I had it set on a cooler temperature, i've had a few cars that needed a recharge but they still blew cool air when the A/C wasn't on.

I think i'll start with the control unit itself, then move my way to the blend door.