AC Novice - need help!

[Irhmsd]

I have a 1974 Porsche 911 TARGA that I am completely restoring. It has factory air conditioning from 1974 and is the BEHR system. I have upgraded the motor from a 2.7 to a 3.2. The original York compressor will not mate to the 3.2 so I already know I need a new compressor. The car is equipped from the factory with both front and rear condensers. These are both original to the car but appeared to be in fine shape. All of the barrier hoses also appear to be original from 1974 so it is safe to assume I will need to upgrade all of those as well. This car will rarely if ever be driven when the roof is on and the windows are not down. Therefore I want to get the air-conditioning system up and running as more of a purist type of a gig then pure performance. There seem to be a lot of options out there with after market upgrade kits. I am simply confused as to which one I should go with and what are the parts that I may need over and above those which I think I have listed. I assume I will need a new receiver dryer. Also assume that I will upgrade the car to R 134 Ok Pelican pals. Let's hear your suggestions. I am a novice and open to input!

[gomezoneill]

I have a compressor and brackets from my 82 sc If you want tem PM me anytime.

[tirwin]

Well these A/C threads tend to end up being a cesspool but I am willing to jump in.

If you're not looking for max performance then a 'path of least resistance' overhaul would be something like this:

- new barrier hose
- pull the condensers and flush them
- consider a new/improved evaporator & TXV (though I'm not sure what would be compatible with your Behr system)
- add a high/low pressure switch
- new receiver drier
- new compressor (if necessary)
- review your A/C electrical system (do you have a blower motor on the front condenser? good idea to put an inline fuse there if you do. check your relays etc.)
- check for leaks and then charge with R134a

This is just a basic outline to get started. Like I said, there may be things specific to your Behr system that others might be able to help with.

If you wanted to improve beyond that then there are, of course, several different options worth considering.

[T77911S]

as above but I am going to add.
mixing old and new parts can be a problem because of the fittings.
I am in the process of having hoses made locally but I am adding 134 fittings to the hoses.
you may have to go this rout so you can have the correct fittings for mixing old and new.
(not sure if they are different).
this could keep you from having to buy all new condensers.

you will probably have to go with a new comp that mounts to the current engine.
you do all this and you are pretty much guarantied no leaks.
have the condensers and evap pressure tested first. then flush them
the TXV should match the refrigerant that you put in. if you want to go 134 this is the tine to do it.,

you could also look out for anewer condensers that would be more efficient than the older ones. I would imagine they are not that good.

[kuehl]

As Tim (Tirwin) suggested is the normal route for stock performance exclusive of evaporator upgrade. Anyone whom fabricates hoses can match up your fittings (flare at deck lid cond, front cond, evap outlet and TEV inlet, and matching your new drier).

I would suggest you pull out your evaporator, inspect the braze joints, clean the fins and reseal the unit in the box (the old factory foam what was inside is gone by now).

For your compressor the 3.2's AC mount is designed for a Denso 911/930 and as you know you will need to find a good used set of compressor manifolds to attach the hoses (84-89 911 manifolds).

Other items to review are your thermostat and evap fan speed switch, by now the contacts on old stock one's are not reliable. Consider replacing the evap motor (its old) and inspecting your primary AC relay in the smuggler's box and contacts for the primary ac fuse and its wire connections.

[tirwin]

Wow, I think we just set a new record for duration of civil discussion in an A/C thread! And today is April 1 too!

Crap. I bet I just jinxed it.

[T77911S]

....

wwest has not found this yet. maybe his computer froze, get it....

[kuehl]

April Fools..... now the fun starts!

[Irhmsd]

OK, thanks for all the input. Here is what I did/am doing. Bought all new Rennaire barrier hoses. Left flared fittings on hoses to match 1974 condensers and evaporator. Had O ring fittings put on the compressor side of the hoses to mate to the Denso compressor. I found a used, recently rebuilt Denso on Pelican with the manifolds included. I also got a Keuhl receiver drier. So, tomorrow, condensers and evaporator will be cleaned out and hoses removed. On Thursday, new hoses, compressor and receiver drier wil be installed. Wish us luck.

[Discseven]

'74 Targa... Nice! If the AC is stock and was run over the years... could be lots of debris where it's not wanted.

A bit of advice... cleaning an evap from the top down can be a mistake. The intake side being on the bottom means the debris build up is on the bottom. And while a down flush on an evap might seem functional, if there's a substantial build-up of debris, it may not dislodge. Best thing to do is either check the bottom of the evap via the intake hole under the passenger's foot rest (stick a small camera in and fire away) or remove the evap entirely for inspection/cleaning.

Another hidden area of interest is above the front condenser. The blower housing has to be removed to check this area.

[Irhmsd]

I may put one of the RennAire evaporators in.