Early 240 a/c upgrading

beno70

Hi all. I’m in a pretty good position to access the hvac system inside the car atm. I’ve been investigating how to replace OE a/c with later components, for assumed efficiency gains and r134 gas compatibility? The existing unit has been out of use for no idea how long, with hoses disconnected in engine bay.

I’ve found a couple TurboBricks posts about the process. And Rock Auto appears to be pretty reasonably priced for a complete new system.

Has anyone attempted this here?

Major Ledfoot

The bigger condenser as fitted to 91+ 240s with the CCOT system comes in LHD and RHD versions. The RHD version is practically unobtanium except from a scrapped car, but the LHD types are available. If using a LHD unit, the pipes would need to be cut off and new ones fitted so it would fit into a RHD car.

I got a new 91+ LHD condenser to see how much work was needed (a fair bit), and to see if it would fit in a pre-91 HVAC unit (it does).

James and others have gotten good results however with the TXV type of condensers - it's worth doing a search on the subject on this forum for what's been done in OZ.

beno70

Major Ledfoot This was more the direction I was thinking, but was unsure about the details. And I've not found a 'how-to' laying out all the newer components needed, and how to plumb together exactly.

I'd read that others upgrading from early 240s had acquired late model firewalls, so guessing this is where the RHD unobtainium edition becomes an issue? I had seen images of the accumulator up close to the firewall (LHD) which differed from my set up (dryer up front near right hand headlight). And I think I've determined that the newer system has the accumulator on the high pressure side, so between evaporator and compressor, hence close to firewall?

Guessing sticking with the early stuff might be an easier path to head down first. I already have a late 80's compressor fitted I think.

jamesinc

Yeah I have what was originally an R12 system. I replaced the Tx valve, the dryer, and replaced the compressor with a Sanden compressor. While I had the system apart, I purged it with mineral turps, dried it, replaced all the o-rings (use Nylog Blue on the o-rings), reassembled and oiled with PAG46 (I think, off the top of my head).

I also added a 10" pusher fan on the front of the condenser to help manage temps at idle.

But the result is that it will cool the cabin right down on even the hottest days. It is not as good as modern AC, but it is pretty good for 1977 components!

beno70

I'll go digging here for more info. (Might resurrect some old threads!)

So did you replace TX valve for refrigerant compatibility? Or just a preventative move?

I've not pulled all the goopy tar tape off it yet, but its very tempting. Straight forward enough to disconnect everything?

jamesinc

Yeah, if you have soft spanners for AN fittings, these are the same sizes.

I would stick to Volvo OEM o-rings as much as possible, or at least genuine Viton o-rings. I had a lot of trouble with ebay o-ring kits.

I replaced the Tx valve mostly as a preventative, if you retain the original you have to adjust the valve spring a few turns, there's a thread on Turbobricks about it.

The tar tape if you need more is known as bitumen cork tape.

beno70

jamesinc Ok, good tips, thanks! Did you pull out the whole system in pieces and clean it all on the bench?

jamesinc

I removed the dryer, and I took the old tx valve, removed the valve from it, then reinstalled it to close up the system. Then I flushed it through using an air compressor and a fluid injector bottle I got on Amazon. The system is split into two open systems so you have to flush them separately, but at least you don't have to pull the evaporator out.