# A/C on 91 HB



## Trogdor (Aug 18, 2007)

Just joined the forums, not sure how I never found this place being a huge Nissan geek my whole life (510's to trucks)
Anyway, my problem is this. Had a leaky A/C system, was a bad low side hose, replaced it. Now when trying to fill the system, the compressor wont kick on at all. Does anyone know how to "jump" the compressor on to make sure it even is going to work? I know there is a low pressure switch that wont allow the compressor to engage if the freon pressure is too low, but I need to bypass this to see if my compressor is failing before I go any further. Thanks for any help you can provide!


----------



## smj999smj (Jan 1, 2006)

First of all, V6 or I4?
Second, did you put the system under a vacuum of 30" for 30 mins. before you attempted to recharge the system? Did it hold the vacuum?


----------



## Trogdor (Aug 18, 2007)

Its the I4..sorry about that. Basically, my buddy (owns a import shop) found the leak,I got a new hose made, and I replaced that. He had it again, cleaned the system out of old oil etc, said there were no leaks, and I was going to put some Freeze 12 in it. I would be asking him, but he is on vacation for a couple weeks, and I have no way to get ahold of him. I have always filled 134a systems so I have put freon in before, but always recharges, never a complete fill.


----------



## smj999smj (Jan 1, 2006)

You need to start out with the system in a vacuum. There can't be any air or moisture in the system when you go to refill.


----------



## spat (Oct 15, 2005)

Check the service manual for info on checking and filling the oil level as well. If your buddy flushed the system you will certainly need to replenish the oil. Now is also a good time to replace the receiver/drier they have a tendency to start deteriorateing after several years. the debris from this can damage the compressor and clog up in the expansion valve. Then vacuum down the system as smj999smj mentioned. After the vacuum down has been completed verify it will hold the 30" for 10-15 minutes. If you loose more than 2"-3" you still have a leak. Or the equipment you are using has a leak, thats a little more tricky. A helpful tip is to use an oil that has dye in it. If you have or later develop a leak it will be much easier to pin point the leak using a black light and special shades available at NAPA and some Parts stores.


----------



## Trogdor (Aug 18, 2007)

It holds vacuum, already put the oil compatible with freeze 12 back in, now it just seems to be a matter of the compressor engaging. It took maybe half a can of freeze 12, and it wont seem to take anymore. I read on a a/c site that getting the compressor engaged will help it vacuum it out of the can.


----------



## spat (Oct 15, 2005)

Trogdor said:


> It holds vacuum, already put the oil compatible with freeze 12 back in, now it just seems to be a matter of the compressor engaging. It took maybe half a can of freeze 12, and it wont seem to take anymore. I read on a a/c site that getting the compressor engaged will help it vacuum it out of the can.


If you have the 2 wire type pressure switch on the receiver/drier then you can unplug it and install a jumper between the terminals on the harness side of the connector (if low pressure opens the switch) or just unplug it (if low pressure closes the switch) I don't remember which way it works I have seen both but don't remember what had which. If you have a 3 wire switch then that is a triple pressure switch and will need to refer to the wiring schematic. Those methods will verify the rest of the system is OK. Another approch is to simply run a jumper straight from battery positive to the compressor clutch. Just be careful of how you rout the wire away from moving parts plus you have to be careful of not letting the compressor run too long or you could exceed the system pressure and blow a line or worse.


----------



## Trogdor (Aug 18, 2007)

So to run the power straight to the compressor, I should just run a wire from the positive terminal to the one wire coming from the compressor correct? Thanks for the help so far, A/C is the one thing totally foreign to me, so thats why all the questions.


----------



## smj999smj (Jan 1, 2006)

Trogdor said:


> So to run the power straight to the compressor, I should just run a wire from the positive terminal to the one wire coming from the compressor correct? Thanks for the help so far, A/C is the one thing totally foreign to me, so thats why all the questions.


Yes....put make sure you have high and low side gauges and monitor them when doing this. When you jump the clutch, you bypass the compressor protection system, meaning it won't shut off unless you disconnect the power regardless of how much the system pressures increase. A clog in the system or stuck expansion valve can limit the amount of freon you can get into the system. It's no fun when a high side hose blows out and your freon and AC oil go blowing all over the place!


----------



## spat (Oct 15, 2005)

LOL..........It's no fun when a high side hose blows out and your freon and AC oil go blowing all over the place!

Yeah my dad had me recharge his A/C last year with one of those small cans. I tried convincing him that if it needed freon it had a leak so he should just take it somewhere for repairs. He kept bugging me about it so I finally charged it for him. But it was nerve racking holding that can in my hand! I wish I still had access to a full shop!


----------



## misindale38 (Sep 19, 2005)

smj999smj said:


> You need to start out with the system in a vacuum. There can't be any air or moisture in the system when you go to refill.



I wrecked my truck awhile back and took out my condensor. I just replaced it recently and filled my system up with freon. It doesnt work. and my high pressure side gets really hot. How would do I vaccume the system without taking it to a shop? I'm 100% positive there is air and moisture in my system as I ran without a condensor for like 6 months. I'm guessing this is why my ac wont work now.


----------



## spat (Oct 15, 2005)

misindale38 said:


> I wrecked my truck awhile back and took out my condensor. I just replaced it recently and filled my system up with freon. It doesnt work. and my high pressure side gets really hot. How would do I vaccume the system without taking it to a shop? I'm 100% positive there is air and moisture in my system as I ran without a condensor for like 6 months. I'm guessing this is why my ac wont work now.


I will reply but in the future it would be better to start a new thread for a new problem.

You would need a vacuum pump and some hoses, not to mention a set of manifold gauges and a regrigerant recovery system. Much cheaper to take it to a shop unless you plan to get into the field of A/C repair. Also from the sound of it a class in A/C repair. 

OK I have critisized enough, but honestly you probably have a lot of work to be done before you get to the point of vacuuming down in preparation for a charge of freon. 

Now that I think of it, post a new thread with detailed info on your truck. Model, Year, Engine, Mileage. Also give details of your problem and how long has the system been exposed to the open atmosphere.


----------



## spat (Oct 15, 2005)

Well I truly was going to offer some help once I got some detailed info. Just wanted to start a new thread to keep from flooding this thread from other issues. and was just offering a little critic because you where heading in the wrong direction.

Yeah, I know the game cocks suck! So What? Thats ancient news!

Take a look at my past posts and you will see I offer the best advice I can and plenty of it.
Yes I do critisize from time to time, but it's all with good intension. 

I will offer you one last peice of advice, talk to "smj999smj" I am sure he can help

I take your advice and now I leave you be! 

Good day!


----------



## misindale38 (Sep 19, 2005)

This "forum" is for questions and answeres. When people come off saying that you should take a class it tends to piss someone off. If I knew all the answeres I wouldnt be on here, and then some one else wouldnt have the benefits of my knowledge. You shouldn't critisize people for asking questions, thats what these forums are for!


----------



## golfer (Aug 21, 2006)

misindale38 said:


> Maybe I'll start off by saying The GameCocks suck ***. You aint gotta be an asshole to answere a question. these forums are for questions you dill hole. Maybe everyone on these forums should take an automotive class, then we wouldnt have to put up with idiots like you!
> Now F OFF!


You sure are over reacting and being an idiot yourself.


----------



## veesix (Jul 18, 2004)

misindale38,

It almost never happens, that someone puts up something as messed-up as your post. 

Profanity and insults,,,WTF?.....No one wants to hear it. 

Plainly put; You messed up big time.


----------



## smj999smj (Jan 1, 2006)

misindale38 said:


> I wrecked my truck awhile back and took out my condensor. I just replaced it recently and filled my system up with freon. It doesnt work. and my high pressure side gets really hot. How would do I vaccume the system without taking it to a shop? I'm 100% positive there is air and moisture in my system as I ran without a condensor for like 6 months. I'm guessing this is why my ac wont work now.


Moisture in the AC system will mix with the freon and form a corrosive acid, which is why it is so important to get it out of the system. Putting the system under a vacuum will boil out the moisture. 

You can get a fairly inexpensive vacuum pump for AC systems from companies like Northern Tools and Equipment and probably J.C. Whitney. They require an air compressor to hook up to in order to work. They also make electric vacuum pumps, but most are very expensive. Also needed, a set of AC gauges to monitor the system, verifying the amount of inches of vacuum and to check for leaks. If there is the potential for dirt inside the AC system, I would recommend flushing the system. Also, regardless of whether it needs to be flushed or not, a new receiver/drier is recommended.


----------



## misindale38 (Sep 19, 2005)

I dont know why I even bother using these forums. Theres like 3 cool users on here. The rest of ya just want to critisize peeps trying to get some info. "good day, eh"


----------



## misindale38 (Sep 19, 2005)

Veesix, kiss off.
Smj999smj, Thank you very much. Thats all I wanted was some helpful advice. Thank you!!


----------



## smj999smj (Jan 1, 2006)

skip...........


----------



## smj999smj (Jan 1, 2006)

misindale38 said:


> Veesix, kiss off.
> Smj999smj, Thank you very much. Thats all I wanted was some helpful advice. Thank you!!


You're welcome!


----------



## veesix (Jul 18, 2004)

Don't feed the trolls!


----------

