Originally posted by Mr.Frugality:
Geoff, when it comes to A/C, and limo's, there can be up to 20 different part's that make up the whole a/c system.
Sometime's the previous owner may have recharged with a can and did not "purge" the line connecting the can to the drier, this add's air to the system which get's caught at top of condensor which can be the cause for poor air, or they could of taken the condensor fan out/fuse, or they might of taken the orifice tube out (this MAY cause the problem you describe and will give wrong pressure reading's), or they may remove the extra condensor, working everything off of the main one.
Make sure you have 2 CONDENSOR'S, 1 LARGE or 2 SMALL EXTRA CONDENSOR FAN'S IN FRONT that work.
Also, if you or anyone (especially those with older limo's) reading this has their limo a/c system opened for any repair or before a re-charge, do what I do:
1) Change the thermal in-line expansion valve ($27) located under partition, stick's out on side of evaporator box, has flat circular end with a copper strand protruding from the center-why? there is a small screen type filter inside that is known to get clogged over time
2) Replace any o-ring ($5/bag) taken off of old part with SAME SIZE new one's (just spray with mineral oil to juvenate)
3) Replace pancake filter $20 (yep another in-line screen type filter)- under hood, follow line FROM rear a/c that goes to condensor-filter will be connected in-between line and is circular in shape
4) Replace in-line liquid 12v solenoid ($35) usually found in-line where line coming FROM condensor goes to rear evap. right before the line meet's the rear evap. it has two elec. wires connected, this is your on/off switch for rear a/c, since it is in-line, it can get "gunk" around the open/close part inside of valve and spring inside under solenoid wear's out from stretching-not opening fully
5) Replace factory a/c system orifice tube ($12) (another filter and refrigerant reducer)
6) Replace factory (and/or aux.) a/c drier/accumulator ($40)
Now you have "tuned-up" your front/rear a/c system. It may sound like a lot, but all the part's listed above are small part's that are easy to change, find, and inexpensive.
To EVERYONE: PLEASE,PLEASE,PLEASE Make sure the person you take it to for repair's is an expert in LIMO ac work and has experience working on limo's!!! Don't take it to Midas, Pepboy's, Advanced Auto, etc...Most of the techs these shop's hire are fresh out of tech school and never touched a limo before!!!
First question I would ask THEM is: Do you have experience in limo ac work? If yes, ask: Can I get a name of a limo company your shop did business with? If yes, call the limo company, nicely ask for the owner, if not available, leave message explaining you were checking the reliability of an ac repair shop that they may have used in the past. If the shop answered NO to any question's above, get out of there, look somewhere else.
Most ac repair shop's for car's don't have the spec. data for limo's pressure reading's. For example: some limo's that have one compressor can give up to 3 different low-side pressure reading's. Example: pressure reading changed when driver's air was turned off and rear air left on, reading also changed when rear air was off and driver's air was on, then again when driver's air is only on vent (not ac but with fan blowing) and rear air is on-ac.
If the tech follow's the wrong reading, the charge will be wrong which can lead to premature compressor failure meaning your compressor will burn out / seize a lot sooner than it was made too.
A trick I learned to get good cold a/c on limo's when temp.s are above 90% is to UNDERCHARGE the system, just a tad below what spec.s call for. About 5-8psi lower on the low-side reading. Don't ask why, I dunno, but I do know these system's do better undercharged. ANY a/c shop that is licensed to recover refrigerant can take some refrigerant (r-134) out.
Here's a link that answer's most a/c question's:
Need to know what limo pressure reading's should be? Go here print for a/c tech: