Pneumatic Air Conditioner Vacuum Pump

[Cofe]

Has anyone here used one of these vacuum pumps...thinking about trying one.

R134a AC Air Conditioning Air Vacuum Pump A C Tool Auto | eBay

 

[GA_Boater]

Re: Pneumatic Air Conditioner Vacuum Pump

I haven't personally, but I had vacuum pulled at a shop once. The tech used it to try it after buying it off the Snap-On truck. The shop owner told him to never use it again because it used so much air. Also it was slow and he ended up using the electrical vacuum pump anyway. I think there is a reason they are inexpensive.

The ad is interesting. I had no idea R134 vacuum was different than R12 vacuum.

 

[mla2ofus]

Re: Pneumatic Air Conditioner Vacuum Pump

Manifold vacuum from the engine works well @ 18"-20" hg.
Mike

 

[Cofe]

Re: Pneumatic Air Conditioner Vacuum Pump

Manifold vacuum from the engine works well @ 18"-20" hg.
Mike

Interesting mla2ofus...would you just hook a intake manifold vacuum line to the guages...How long should one hold a vacuum ..."I would put a question mark back there, but my question mark on my keyboard is defunct."

 

[MTboatguy]

Re: Pneumatic Air Conditioner Vacuum Pump

I have one, don't buy one, they don't work worth a crap, take way to much air, they are not even worth it with my set up, which is a 79 gallon 8 hp set at 125PSI, I bought one, tried it once and gave it away and the person I gave it to, gave it away.

 

[Cofe]

Re: Pneumatic Air Conditioner Vacuum Pump

Thanks for the heads up MTboatguy...but the motor vacuum hook up mentioned before has me curious.

 

[mla2ofus]

Re: Pneumatic Air Conditioner Vacuum Pump

Interesting mla2ofus...would you just hook a intake manifold vacuum line to the guages...How long should one hold a vacuum ..."I would put a question mark back there, but my question mark on my keyboard is defunct."

Just find a hose that reads high vacuum and connect to the gage manifold. After 5 or so min close the valve and see if it leaks down. If no leak then open valve and maintain vacuum for 1/2 hr or so. Close valve and check again for leakdown. If still no leaks then start adding Freon and oil, if it's needed.
Mike

 

[bigdee]

Re: Pneumatic Air Conditioner Vacuum Pump

Manifold vacuum from the engine works well @ 18"-20" hg.
Mike

You need 29" hg to boil off water at 60 degrees. The pneumatic pumps work well if you have enough compressor to handle it. A better alternative is a electric vacuum pump from Harbor Freight. I recently bought one for $75 with a 25% coupon and it will pull down to 30"hg.

 

[dolluper]

Re: Pneumatic Air Conditioner Vacuum Pump

Had to use a cheapyer one than that at the shop while waitibg for parts on pro unit electric.......did the job but took alot longer.....home non=commerical use it would be worth it....save you alot of bones

 

[jspriddy]

Re: Pneumatic Air Conditioner Vacuum Pump

I had a really great one made from an refrigerator compressor pump one time. It would pull an auto system down to 29 easily. An appliance repairman made it for me. Had to have some kind of condenser or something on the power supply (I'm not too up on that, but it looked simple) and a male connection soldered on the vacuum (low side) line. I later added a connection on the high side to pump up systems to find leaks. This was very useful after freon got so high, price-wise.

 

[bigdee]

Re: Pneumatic Air Conditioner Vacuum Pump

I had a really great one made from an refrigerator compressor pump one time. It would pull an auto system down to 29 easily. An appliance repairman made it for me. Had to have some kind of condenser or something on the power supply (I'm not too up on that, but it looked simple) and a male connection soldered on the vacuum (low side) line. I later added a connection on the high side to pump up systems to find leaks. This was very useful after freon got so high, price-wise.

I made one years ago when refrigerator compressors ran R12 and were 1/4 hp. Newer compressors are too wimpy to make a good vacuum pump. When you can buy a 2.5 cfm vacuum pump for less than $100 why bother.

 

[jspriddy]

Re: Pneumatic Air Conditioner Vacuum Pump

I made one years ago when refrigerator compressors ran R12 and were 1/4 hp. Newer compressors are too wimpy to make a good vacuum pump. When you can buy a 2.5 cfm vacuum pump for less than $100 why bother.

Because the refrigerator pump was essentially free. Everything he used to make it was just stuff lying around his shop. What was the capacity of the compressors then (25 years ago) compared to now? Do modern refrigerants require less pressure, hence less powerful pumps? I'm asking, since I haven't worked with air conditioning in years.

By the way, for someone who wants to make one, I just looked and some freezers have compressors up to 1/2 hp, so this shouldn't be an issue. If you pick one up for whatever, $10-15, the difference is just that much you've saved.

John

 

[bigdee]

Re: Pneumatic Air Conditioner Vacuum Pump

Because the refrigerator pump was essentially free. Everything he used to make it was just stuff lying around his shop. What was the capacity of the compressors then (25 years ago) compared to now? Do modern refrigerants require less pressure, hence less powerful pumps? I'm asking, since I haven't worked with air conditioning in years.
John

Newer ones run a higher pressure b/c they usually use r134. However the efficiency has improved dramatically over the last 20 years so that is why less hp is needed. Older refrigerators had a shorter duty cycle and would cycle off and on where as the newer ones run 80% of the time...that is one of the keys to efficiency.

 

[jspriddy]

Re: Pneumatic Air Conditioner Vacuum Pump

...Newer compressors are too wimpy to make a good vacuum pump.

Newer ones run a higher pressure b/c they usually use r134. However the efficiency has improved dramatically over the last 20 years so that is why less hp is needed. Older refrigerators had a shorter duty cycle and would cycle off and on where as the newer ones run 80% of the time...that is one of the keys to efficiency.

Come on, Bigdee. Which one is it? Are the newer compressors "too wimpy" or are they "improved dramatically"? If they run higher pressure, then it would stand to reason they would pull a stronger vacuum. Or are you saying they wouldn't stand up over time used as a vacuum pump?

John

 

[matt167]

Re: Pneumatic Air Conditioner Vacuum Pump

No, compressor displacement has decreased.. R134A does not need the volume that R-12 did, but they run at a higher pressure.. Big reason on why the old auto systems were power hungry.. I have the compressor from a 1975 Lincoln. Never figured out what to do with it, but put it on the shelf for a someday project

 

[bigdee]

Re: Pneumatic Air Conditioner Vacuum Pump

Come on, Bigdee. Which one is it? Are the newer compressors "too wimpy" or are they "improved dramatically"? If they run higher pressure, then it would stand to reason they would pull a stronger vacuum. Or are you saying they wouldn't stand up over time used as a vacuum pump?

John

Matt is correct. It all about displacement which equal volume. Both systems will pull down to the same vacuum but the newer r134 compressors will do so with less volume which means it will take longer to evacuate whatever system it is that your trying to service. In order to reduce hp and at the same time increase pressure volume has to be reduced. This reduced volume is why refrigerators NEED to run 80% of the time. It takes a long time after the compressor starts to reach optimal efficiency.

 

[jspriddy]

Re: Pneumatic Air Conditioner Vacuum Pump

Matt is correct. It all about displacement which equal volume. Both systems will pull down to the same vacuum but the newer r134 compressors will do so with less volume which means it will take longer to evacuate whatever system it is that your trying to service. In order to reduce hp and at the same time increase pressure volume has to be reduced. This reduced volume is why refrigerators NEED to run 80% of the time. It takes a long time after the compressor starts to reach optimal efficiency.

OK, now I see. When 134 came out, I was making other changes in my business as well. As R12 systems left the market, I just eased out of A/C service.

You just had me confused with your two seemingly contradictory statements.

Thanks,

John

 

[hrdwrkingacguy]

Re: Pneumatic Air Conditioner Vacuum Pump

It's all about net refrigeration effect...compressors are vapor pumps rated in cfm. Different refrigerants are bigger or smaller and require different amounts of energy to compress. R410a is a bigger molecule then r-22 but requires less energy to compress. So you end up with a larger system that requires less kW to do the same job...r12 and 134a are a similar relationship. 1# of 134a at the same pressure is something like 11(probably wrong on the exact number) times larger then 1# of r12...which is why you can't put 134a in a r12 system and have it be the same capacity...

as far as 134a vacuum vs 12 vacuum that's just the dumbest thing I have ever heard. Evacuation isn't about refrigerant it's about moisture...if your only pulling something to 28" your not boiling off the moisture...to big a pump and to fast of a vacuum will freeze moisture...

 

[bigdee]

Re: Pneumatic Air Conditioner Vacuum Pump

as far as 134a vacuum vs 12 vacuum that's just the dumbest thing I have ever heard. Evacuation isn't about refrigerant it's about moisture...if your only pulling something to 28" your not boiling off the moisture...to big a pump and to fast of a vacuum will freeze moisture...

Whoa, not too fast there! Evacuate on my terms is MOISTURE. I did not say refrigerant, so don't try to misinterpret what I'm trying to explain. I agree with you about 28"hg not boiling off moisture...unless it is 100 degrees or more ambient temperature.

 

[hrdwrkingacguy]

Re: Pneumatic Air Conditioner Vacuum Pump

The ad is interesting. I had no idea R134 vacuum was different than R12 vacuum.

I was referring to the article. Not what you said. I was also referring to the evacuation process. Techniques aren't different for application or refrigerant. Obviously a cascade system for cryogenics is different then a car system.