Replacing AC Compressor

[Fred Cook]

 My AC compressor froze up and busted my serpentine belt. We are currently stranded 100 miles away from home at a friend’s house. I want to replace it myself. Is there a way to do this without losing all my R134?

[Mike Shumack]

You can not replace the compressor without first evacuating the refrigerant.

However, if you only need to replace the pulley/clutch assembly (i.e the parts in the pic below), you can do that without removing the compressor and disconnecting any lines.

[Fred Cook]

You can not replace the compressor without first evacuating the refrigerant.

However, if you only need to replace the pulley/clutch assembly (i.e the parts in the pic below), you can do that without removing the compressor and disconnecting any lines.

 Thanks for the info. Looks like I will have to drain the lines. I suppose it will be OK to operate the unit without any R134 in it until later. Is that correct?

[Doug Allman]

We have replaced our compressor 3 times on our 2004 Marquis and each time I believe we had to because of low refrigerant is why it burned up. Looked at doing just the clutch repair but due to relative cost just decided to do it with new compressor and try to figure out why loosing refrigerant. Actually I do not know or believe if you can ever get the dash air right on a coach as we spent a lot of $$$$ trying to.
Someone with more expertise on A/C than I can comment but I believe that loss of refrigerant is why the compressor burns up. I am not sure if when you start to not get cold air you can leave it turned off and get more refrigerant added so you do not burn up compressor. Comments please .

[Jim Nichols]

Napa Auto/Truck stocks the compressor assy. Clutch assy would have to be ordered. Compressor comes filled with oil. 2 coolant lines, 4 bolts, disconnect clutch wires, and belt is probably gone. Pump is $300 and belt about $35. Leave clutch disconnected until recharging.

[Dave Atherton]

Gentleman, AC compressor lock up can occur from over filling coolant to system without vacuum AC
System than recharging system. Many will cap off cooling system with these little cans of coolant.
There is a few factors that come into play between the high pressure and low pressure along with compressor. Dave Atherton Retired Cat Mechanic

[Mike Shumack]

 Thanks for the info. Looks like I will have to drain the lines. I suppose it will be OK to operate the unit without any R134 in it until later. Is that correct?

The unit will not operate without refrigerant in it, of course.

It is okay to leave the compressor in place and drive the coach. I believe you said the belt broke from the compressor pulley seizing. If this is the case you can just leave the belt off - as long as that belt does not also turn other things (like the Alternator and/or water pump). I don't recall what engine you have (and I cant look until finish this post).

One of the reasons these AC compressor replacement jobs fail, is that when the system leaks refrigerant "oil" is lost. It is impossible to know how much oil was lost. Most shops doing a quick repair (i.e. replacing a hose or such) will add some oil back into the system during a recharge, but if too much oil is added the system won't cool properly, and if too little oil is added the compressor burns up (in a short time).

The proper way is to drain all the oil out (either remove the compressor, evaporator, condenser, and receiver/drier and drain - or flush everything thoroughly) then add in the correct amount of oil, putting some in each component). Also, note that a replacement compressor will typically come with oil in it - but that doesn't mean the entire system will have the correct amount of oil after the compressor is installed.

The other challenge in doing AC work on these coaches, is that the "universal AC charge guides" don't have a listing for a Beaver (Monaco, etc.) so the shop doesn't know (can't look up) what the correct amount oil is - or the correct amount of refrigerant to add. If there is a decal with this info on the evaporator housing - you're lucky but many times this decal is gone or ineligible due to age. Fortunately the Owners Manual has this info (at least mine does) and although general it is still useful if that decal is gone.  Note how much additional (over a typical truck or car AC system) oil is needed due the 80+ feet of AC hose used on these coaches.

[Steve Huber]

Mike,
On the 05, where are the high and low side ports, front or rear of the coach? Pressure readings will differ so curious to know where 200PSI is read.
Steve

[Mike Shumack]

On the '05 the ports are located at the compressor (about 6 inches away from the compressor on the AC lines).

[Stan Simpson]

The last time I had a shop do a check for leaks, and a re-charge, they called Monaco and asked them how many lbs. (?) of refrigerant was max. IIRC it was 4-1/2 or 5.

[Gerald Farris]

Fred,
You do not need a serpentine belt to drive a C 12 as long as you keep the generator running to charge your batteries. If you are using the Echo Charger system, you will have to hold down the boost switch periodically or run a jumper from the house battery positive cable to the chassis battery positive cable because your coach will use more than the 15 amps that it can supply to the chassis batteries.

In the 175,000 miles that I drove my 2000 Marquis, I had 2 A/C compressor failures and one idler pulley bearing failure that resulted broken serpentine belts. So I just cranked the Onan and keep driving. The C 12 powers all necessary components from the timing gears except the alternator, so as long as you can charge your batteries, you do not need the serpentine belt.

Gerald   

[Fred Cook]

Fred,
You do not need a serpentine belt to drive a C 12 as long as you keep the generator running to charge your batteries. If you are using the Echo Charger system, you will have to hold down the boost switch periodically or run a jumper from the house battery positive cable to the chassis battery positive cable because your coach will use more than the 15 amps that it can supply to the chassis batteries.

In the 175,000 miles that I drove my 2000 Marquis, I had 2 A/C compressor failures and one idler pulley bearing failure that resulted broken serpentine belts. So I just cranked the Onan and keep driving. The C 12 powers all necessary components from the timing gears except the alternator, so as long as you can charge your batteries, you do not need the serpentine belt.

Gerald   

 This is great information Gerald. It’s nice to have a coach that will not cause serious damage when a belt pops off.

[Larry Dedrick]

Fred
      Strongly recommend that you make sure your replacement compressor is Sanden U.S built compressor. The Sanden TYPE or Sanden LIKE are not from Sanden. The Type and Like are Chinese knockoffs.
       Had mine replaced and had to Insist on Sanden U.S. built out of Texas.
       Do not buy it from a coach supplier, very expensive.  A/C Parts Warehouse have the U.S. built for $289.00. Same compressor from Monaco was close to $900.00

       For what it's worth
               Larry D.

[Fred Cook]

Fred
      Strongly recommend that you make sure your replacement compressor is Sanden U.S built compressor. The Sanden TYPE or Sanden LIKE are not from Sanden. The Type and Like are Chinese knockoffs.
       Had mine replaced and had to Insist on Sanden U.S. built out of Texas.
       Do not buy it from a coach supplier, very expensive.  A/C Parts Warehouse have the U.S. built for $289.00. Same compressor from Monaco was close to $900.00

       For what it's worth
               Larry D.

 Thanks Larry. The brand name on my ordered compressor is Seltec.  I paid $331 which included 2 day shipping.  Picking it up tomorrow. Don’t know much about it.... is that a good compressor?

[Mike Shumack]

Are you planning to just replace the compressor, or do you have other parts too (like the Receiver-Drier).
Are you going to flush the system?