Harbor freight vacuum pump

[Farmall m farmer]

Does anybody have any experience with them I want to pull vacuum on a ac system in a truck and convert it from r12 to r134a will they work for that? Are they any good what’s the difference in the $100 one compared to the $150 one

 

[Hobo,NC]

Does anybody have any experience with them I want to pull vacuum on a ac system in a truck and convert it from r12 to r134a will they work for that? Are they any good what’s the difference in the $100 one compared to the $150 one

This guy has been posting some videos on it. He's the man in the HVAC world.

Tom Lech / LECH AIR CONDITIONING

HVAC tools, tips, training, procedures long forgotten and never tough in the automotive trade. Using the best equipment to preform the fastest quality job for your customer. I'm learning about videos, sound, lighting, will get into video and sound editing to improve my videos to you. My trade...

www.youtube.com

 

[FarmallM51]

I've used one for years, and had no problems with it.
Marlin

 

[Fred Werring]

Does anybody have any experience with them I want to pull vacuum on a ac system in a truck and convert it from r12 to r134a will they work for that? Are they any good what’s the difference in the $100 one compared to the $150 one

I bought the single stage (cheaper) maybe 10 years ago, done 6 or so compressors with it, been fine.

EDIT...a quick search on Amazon found a single stage $30 cheaper than Harbor Freight. Got good reviews. Don't know anything else about it. Just be sure to try it out before 30 days are up so you can return it to Amazon if needed rather than the manufacturer.

Vacuum Pump

 

[NoDakInMN]

Having not seen the pumps to know for sure, I suspect the difference in cost is due to the capacity of the pump. Automotive/tractor AC systems are pretty small in overall relation to other HVAC systems, so you don't need a very big and more expensive pump to do the job. One with a rating of 3 cfm or a little less would be more than adequate.

 

[jimg.allentown]

Either pump will probably get the job done adequately. The main difference will be the level of vacuum they will achieve.
To be technically "legal," you should have the R-12 recovered at a shop with a recovery machine. The advantage to that would be that a recovery machine will also remove most of the oil in the system.

A word about oil. Everything in an R-12 system will work just fine with R-134a - except for the oil. The mineral oil used with R-12 circulates with the refrigerant to lube the compressor. That oil will not circulate with the R-134a. For that you need to use the ester oil that is recommended for use with R-134a.

Also note that if this is/was a functioning R-12 system, there should not be any significant amount of moisture in the system that would otherwise be removed by a pump that achieves a deeper vacuum. The main thing the vacuum will accomplish is to remove the air from the system if it has been opened.

 

[Eman85]

Finding a shop that can recover R12 will be a chore, most of those machines are in the scrap pile by now. Chances ar the R12 in his system is busy causing our sunburn today and has left the system.

 

[bc]

I looked at them earlier this summer. Cheaper one is 2.5 cfm single stage and next one is 3 cfm two stage pump. 2 stage is better. I ended up ordering on Amazon and got a kit with a bigger pump and gauges and leak detector for the same money around 150 bux. They will all pull an adequate vacuum but not the deep vacuum micron level the experts want you to have with the big recovery machines. I read a bunch of reviews and watched a bunch of you tube videos where people have used single and two stage pumps to do what you want to do.

 

[jimg.allentown]

Finding a shop that can recover R12 will be a chore, most of those machines are in the scrap pile by now. Chances ar the R12 in his system is busy causing our sunburn today and has left the system.

I only pointed this out because it is technically illegal to release R-12 into the atmosphere. Also, we should all be aware that R-21 is still wifely in use in third world countries - like most of the countries in South America and Africa. The REAL reason we phased it out here was that DuPont's patents and copyrights expired on the R-12. Same thing with R-22 and now coming up on R-134a.
Those are being replaced by refrigerants that are highly flammable.

 

[NoDakInMN]

Either pump will probably get the job done adequately. The main difference will be the level of vacuum they will achieve.
To be technically "legal," you should have the R-12 recovered at a shop with a recovery machine. The advantage to that would be that a recovery machine will also remove most of the oil in the system.

A word about oil. Everything in an R-12 system will work just fine with R-134a - except for the oil. The mineral oil used with R-12 circulates with the refrigerant to lube the compressor. That oil will not circulate with the R-134a. For that you need to use the ester oil that is recommended for use with R-134a.

Also note that if this is/was a functioning R-12 system, there should not be any significant amount of moisture in the system that would otherwise be removed by a pump that achieves a deeper vacuum. The main thing the vacuum will accomplish is to remove the air from the system if it has been opened.

Any vacuum pump is capable of pulling a deep vacuum, larger ones just do it quicker because of their greater capacity. If you can't reach deep vacuum with a vacuum pump, large or small, you have a leak or moisture. If moisture is present in a system, any vacuum pump will remove it, again size doesnt matter, it just takes longer with a smaller pump. Of course, if the vacuum oil turns milky from the moisture, you need to change the oil as it's ability to pull a vacuum has been greatly reduced. Sometimes several changes are necessary until you can pull a deep vacuum with clean oil. As a vacuum allows moisture to boil at room temps, the level of vacuum will stall out until all the moisture is removed, then it can go deeper. A 3 cfm pump, which is at the lower end of capacity ratings, is more than adequate for automotive type applications because they are small systems relatively speaking. I carried a 3 cfm pump for years in my van and it worked fine on much larger systems than automotive.

If you are working in humid conditions and the system has been open for some time, purging the system with dry nitrogen first will speed up evacuation time as it takes longer to remove moisture laden air.

 

[NoDakInMN]

Finding a shop that can recover R12 will be a chore, most of those machines are in the scrap pile by now. Chances ar the R12 in his system is busy causing our sunburn today and has left the system.

You don't need a special recovery machine for R-12 because the principal of operation is the same for all refrigerants unless you get into stuff like ammonia. But yeah, the odds of an automotive system having R-12 still in it is pretty slim.

 

[jimg.allentown]

Any vacuum pump is capable of pulling a deep vacuum, larger ones just do it quicker because of their greater capacity. If you can't reach deep vacuum with a vacuum pump, large or small, you have a leak or moisture. If moisture is present in a system, any vacuum pump will remove it, again size doesnt matter, it just takes longer with a smaller pump. Of course, if the vacuum oil turns milky from the moisture, you need to change the oil as it's ability to pull a vacuum has been greatly reduced. Sometimes several changes are necessary until you can pull a deep vacuum with clean oil. As a vacuum allows moisture to boil at room temps, the level of vacuum will stall out until all the moisture is removed, then it can go deeper. A 3 cfm pump, which is at the lower end of capacity ratings, is more than adequate for automotive type applications because they are small systems relatively speaking. I carried a 3 cfm pump for years in my van and it worked fine on much larger systems than automotive.

If you are working in humid conditions and the system has been open for some time, purging the system with dry nitrogen first will speed up evacuation time as it takes longer to remove moisture laden air.

I have to disagree about whether "any" pump will reach the same level of vacuum. It is not just a matter of time. It is also a matter of how capable the pump is. Needless to say, some pumps are more able to reach a deep vacuum, and some may never be able to reach the same level as a more "precision" pump for lack of a better word. Needless to say, a multi stage pump will usually pull a deeper vacuum than a single stage pump. So also will a diffusion pump pull a deeper vacuum than any of them.

However, we are splitting hairs here. Unless there is enough moisture in a system to cause internal freezing, it just isn't a big factor. Non-condensible gases would ba a bigger concern. But, at the end of the day, just about any pump will do the job sufficiently for the system to operate properly.

 

[Watthour]

... Everything in an R-12 system will work just fine with R-134a - except for the oil...

There is one additional caveat to that. While the hardware designed for an R-12 system will work, the hoses may not be quite the same. Within R-12 systems that were designed or installed until very late in the product life cycle, the hoses were not barrier hoses. That made very little difference for R-12, but R-134A molecules are much smaller, and can permeate the "early" hoses designed for R-12. If your converted system seems to lose charge every few months with no apparent or identifiable leakage points, it might be the hoses. UV dyes will not help with this, since R-12 hoses will stop the common UV dyes from permeating while letting the refrigerant filter through.

If you question this, perform a search for ""R-134A barrier hose" and grab a cup of coffee. You might be enlightened. There is/was a whole industry dedicated to this, with the likes of Gates, Robinair, Goodyear, and others playing along.

 

[bc]

There is one additional caveat to that. While the hardware designed for an R-12 system will work, the hoses may not be quite the same. Within R-12 systems that were designed or installed until very late in the product life cycle, the hoses were not barrier hoses. That made very little difference for R-12, but R-134A molecules are much smaller, and can permeate the "early" hoses designed for R-12. If your converted system seems to lose charge every few months with no apparent or identifiable leakage points, it might be the hoses. UV dyes will not help with this, since R-12 hoses will stop the common UV dyes from permeating while letting the refrigerant filter through.

If you question this, perform a search for ""R-134A barrier hose" and grab a cup of coffee. You might be enlightened. There is/was a whole industry dedicated to this, with the likes of Gates, Robinair, Goodyear, and others playing along.

And that begs the question, when did the auto manufacturers realize this and change the rubber hose they installed? I suspect there are some vehicles in the 90s or whenever that had the wrong kind of hose.

 

[RobCons]

I have a HF pump, cant remember the model though, and it works great. I've done several A/C units with it.

 

[Watthour]

And that begs the question, when did the auto manufacturers realize this and change the rubber hose they installed? I suspect there are some vehicles in the 90s or whenever that had the wrong kind of hose.

Vehicles started phasing out R-12 in the 1993 model year (1992 calendar) so manufacturers and suppliers were probably only switching over about that time, or perhaps only shortly before then. That means that about 1/3 of 1990's vehicles were R-12 types.

Also, it wasn't the "wrong" kind of hose for R-12 since it had been working successfully for several decades. "Incompatible" is probably a more accurate term.

 

[Farmall m farmer]

I got unlucky that mines a 91 so there was a 66% chance of r134a and I got r12 story of my life

 

[NoDakInMN]

I have to disagree about whether "any" pump will reach the same level of vacuum. It is not just a matter of time. It is also a matter of how capable the pump is. Needless to say, some pumps are more able to reach a deep vacuum, and some may never be able to reach the same level as a more "precision" pump for lack of a better word. Needless to say, a multi stage pump will usually pull a deeper vacuum than a single stage pump. So also will a diffusion pump pull a deeper vacuum than any of them.

However, we are splitting hairs here. Unless there is enough moisture in a system to cause internal freezing, it just isn't a big factor. Non-condensible gases would ba a bigger concern. But, at the end of the day, just about any pump will do the job sufficiently for the system to operate properly.

Been doing commercial/industrial HVAC for 40+ years and carry a CM rating from the Refrigeration Service Engineers Society. So, I do have some expertise in these matters. I've never seen a vacuum pump that was rated for HVAC use and in good working order that wasn't able to pull a deep vacuum. Higher cfm ratings and two stages simply increase the capacity and efficiency but does not increase the depth of vacuum that can be obtained. We measure vacuum with micron gauges and I have seen small single stage pumps get down to 1,000 microns. People have said they have pulled as low as 250 or 500 microns, but I don't believe that is a vacuum they were able to hold very long because refrigerant oils start to boil off at around 750 microns.

Acceptable moisture levels in refrigeration systems are measured in PPM or parts per million and vary by application, but it is lower than just enough to prevent internal freezing because that indicates a pretty bad case of moisture contamination. This is because moisture affects more things than just freezing up metering devices. Liquid refrigerant is a solvent and any areas exposed to it are subject to rust and corrosion from trace amounts of moisture. It also breaks down the oils used in the systems and under certain conditions can create adverse chemical reactions with the refrigerant. That is why we install driers even after achieving deep vacuum, to prevent these additional detrimental effects of moisture.

Now, automotive systems don't always get treated as well as larger systems, and they suffer from vibration and other forces that come with being installed in vehicles, but they do benefit from more stringent practices.

 

[NoDakInMN]

Vehicles started phasing out R-12 in the 1993 model year (1992 calendar) so manufacturers and suppliers were probably only switching over about that time, or perhaps only shortly before then. That means that about 1/3 of 1990's vehicles were R-12 types.

Also, it wasn't the "wrong" kind of hose for R-12 since it had been working successfully for several decades. "Incompatible" is probably a more accurate term.

The change in refrigerants was mandated by US government policy, and as is often the case with the government, the policies timelines were not based on the industry's ability to comply with them, but on the wishes and dreams of bureaucrats totally ignorant of the field that they were regulating. Consequently things got rushed into production before all the consequences were understood. I worked for Trane corporate for many years, and the story is told that when they tested R-123, the replacement for R-11, which was used in our large centrifugal chillers, they put the new refrigerant in the R-11 machines and ran them until they broke and then they tore them down to see what failed. This is the kind of a$$ backward engineering the government forced on the industry.

So, it was quite likely the car manufacturers were not aware of the hose incompatibility issue until failures began to occur.

 

[Hdonly]

I made a vacuum pump from an old refrigerator compressor. Works great. I have been using this method for many, many years. Much cheaper and works just as well as a manufactured pump.