Is this my AC vacuum pump?

[CoCoDave]

Thanks to AtlantaRick for sending me his old vacuum generator. I should have known that Mike would have nailed the principle of operation. It does indeed have a small venturi that creates a partial vacuum when compressed air is pushed through it. I still do not know why a correctly functioning one "flutters" or "pulsates" like it was a reciprocating pump.

Rick's works to the extent that when 12VDC is applied the solenoid valve opens allowing the compressed air into the venturi. But the vacuum generated is very anemic and never reaches the level that will open the switch to shut off off the solenoid.

I did find a part number and source for the switch if one knew for certain that his switch was bad. However, it probably makes the most sense to replace the whole thing with a 12VDC vacuum pump as Rick did.

Vacuum Actuated Switch MVS3 is the one we want.

Thanks again Rick, for sending the old vacuum generator.

Best,

[AtlantaRick]

Dave. You figured out more than I could have. If I had to do it again I would get the cheap one from NAPA or some internet site.... but hindsight is 20/20. I am just glad it is done and I am getting cold air in my face.

[allend]

hi
new to this forum. i have a 2001 HR ambassador. i had the same problem with the vacuum pump. in the process of solving it the vacuum hoses came off the selection switch on the dash. the vent, defrost, ac, etc. any body have a picture of the hoses position or know where i can get a diagram of the connections. it sure would help.

[Skip426]

Originally Posted by allend

hi
new to this forum. i have a 2001 HR ambassador. i had the same problem with the vacuum pump. in the process of solving it the vacuum hoses came off the selection switch on the dash. the vent, defrost, ac, etc. any body have a picture of the hoses position or know where i can get a diagram of the connections. it sure would help.

allend; Welcome to iRV2 .

Any time you have a question that isn't directly the same as the one posted originally , you should start a new thread ( post ) ; more people will see it and respond; because most don't read every post before adding their own to a thread .
Any way without knowing your dash air supplier , there are a couple of possibles , but since you say vacuum , I'm assuming ,Evans-Tempcon made your dash air.

Evans Tempcon, Inc - Service Parts

Sorry thought photo was the vacuum diagram , and it's wiring , I'll track down the correct photo and re-post.

[BFlinn181]

Originally Posted by allend

hi
new to this forum. i have a 2001 HR ambassador. i had the same problem with the vacuum pump. in the process of solving it the vacuum hoses came off the selection switch on the dash. the vent, defrost, ac, etc. any body have a picture of the hoses position or know where i can get a diagram of the connections. it sure would help.

Like Skip said, you might contact Evans Tempcon Tech support if you find your dash control is one of theirs.

The other option would be to do it by trial and error. The supply hose would be the only one with vacuum present. Hook it into each location on the panel back until it's in the proper one. Then put control on dash vents, try each of the remaining hoses until air comes out only the dash vents. By trial and error you should be able to connect the hoses to the proper switch.

[C-PHartley]

These pumps are not continuous duty pumps. Therefore it is important to check for any leaks, so that you don't burn up the new one. I just went thru this. I checked for leaks by sealing off the pump inlet to ensure that it would cut off. Then I added hoses and components one at a time to verify that it would still cut off. I found several leaks in old hoses and a valve in the dash controller. I'm sure that this is what contributed to my failure.


Sent from my iPad using iRV2 - RV Forum

[allend]

Wow

thanks for all the responses. I had to buy one of those dorman pumps after finding the old pump didn't give enough vacuum. it already installed and working fine. i can hear it shut off after it builds up the vacuum. The black hose is the main vacuum and it goes in the center hole in the picture if I can add pictures. I have already tried different connections but I could never get the air to stop coming out of the defrost. did get air to come out of the vents and defrost and some floor. don't know if my doors are working properly but if i can get the hoses to the right holes i can at least eliminate that part and then know if it the doors or vacuum actuators. again thanks for any help. it is a evans temp and if i have to i will go there next. i have edit this because i couldn't add pictures or don't see where they are.

allen

[allend]

hi
thanks skip426. i went to the link you gave me. couldn't find any pictures of vacuum hoses connections. did find ph # for tech support. will try and call them tomorrow. in the mean time what am i doing wrong to post pictures.

allen and thanks

[Skip426]

Originally Posted by allend

hi
thanks skip426. i went to the link you gave me. couldn't find any pictures of vacuum hoses connections. did find ph # for tech support. will try and call them tomorrow. in the mean time what am i doing wrong to post pictures.

allen and thanks

Not 100% sure why some members have issues posting pictures , sometimes they just come on to the post sideways.
Any how I was looking for a picture of the vacuum system , and it's a pdf .

[allend]

skip

thank you for the vacuum diagram. i was able to make my connections and then heard my pump running constantly. After trying each hose by itself i discovered all hoses good and no leaks. i'am thinking the leak is at the junction box where all the hoses connect, or, it the selection switch box itself. Hopefully i'm going to connect the hoses directly to each port eliminating the junction box altogether and if it still leak then that will confirm it is the switch and if the leak stop, then it was the junction box.

allen