The great 240 AC system information dump + How to improve AC performance

[VolvoLatAm]

I am in the process of buying a new Sanden AC compressor. There are 5 cylinder and 7 cylinder v-port compressor options in Colombia with your standard clutch activation wire.

They are all the same price here with a variance of 25 or so dollars. Singaporean & American variants. No Japanese.

I have read through the dave barton article:
https://www.240turbo.com/classicair.html
but he does not mention the significance of inter-bracket distance on available universal compressors.

Looking at the diagram I am following in imgur link, besides the clutch style (2 ring pulleys or one large one) there is a spacing difference on the built-in universal compressor brackets.

[Diagram, desired setup, and compressor availability in my country]: https://imgur.com/a/8O6Rsrd

Measuring the inside from bracket to bracket (red lines displayed in this diagram), there are many product bracket variants of 6-6.5cm, 7-7.5cm, and 8cm.

I have all of the brackets/bushings/hardware available for the ac compressor install on my left-fitted ac/alternator block bracket...

Just wondering which compressor bracket inter-distance spacing in cm that I should aim for?
It seems like it could affect the alignment with the pulley or maybe it all can just be adjusted...?

 

[apachechef]

I am in the process of buying a new Sanden AC compressor. There are 5 cylinder and 7 cylinder v-port compressor options in Colombia with your standard clutch activation wire.

They are all the same price here with a variance of 25 or so dollars. Singaporean & American variants. No Japanese.

I have read through the dave barton article:
https://www.240turbo.com/classicair.html
but he does not mention the significance of inter-bracket distance on available universal compressors.

Looking at the diagram I am following in imgur link, besides the clutch style (2 ring pulleys or one large one) there is a spacing difference on the built-in universal compressor brackets.

[Diagram, desired setup, and compressor availability in my country]: https://imgur.com/a/8O6Rsrd

Measuring the inside from bracket to bracket (red lines displayed in this diagram), there are many product bracket variants of 6-6.5cm, 7-7.5cm, and 8cm.

I have all of the brackets/bushings/hardware available for the ac compressor install on my left-fitted ac/alternator block bracket...

Just wondering which compressor bracket inter-distance spacing in cm that I should aim for?
It seems like it could affect the alignment with the pulley or maybe it all can just be adjusted...?

what hoses are you using?
Do you need v-port?
what car is it going into?
why are you contaminating a 240 with a 7/9 bracket?
Do you have Power steering?
Where is you alt now?

the rear "ears" on the compressor and the thin steel curved brackets can be flipped around to fit the different compressor, to an extent. the 1991-2 vs the 1993 only bracket are like this on 240s. seems like a suboptimal can of worms to use a 7/9 bracket.

bring your big 7/9 mount in and see how it lines up with accessory bushings and steel brackets, and pick the next headache you will need to tackle by using the wrong 7/9 part.

if you are making own hoses, things are much simpler, Sandens have interchangable heads on the rear that can direct hoses in many other directions.

before you complain about this answer, note that I have done this, several times, on different 240's. Give more data, and explain why you are doing things that are not ideal

 

[Cwazywazy]

bump

Until last week, I hadn't touched my AC since I charged it after installing the new Sanden two years ago. I put in 12oz of Envirosafe and it really wasn't any better than with the old compressor. Maybe 55-60 out the vent running down the road and ~65 parked. I recently picked up a cheap reclaimer machine which lets me suck the juice out so I can fiddle with things, then put it back in. No buying new refrigerant or worrying about disposal. It's pretty sweet.

So far I've messed with the TXV adjustment and I swapped it out for an old original r12 TXV. This did change the low side pressure, but basically did nothing for vent temps. Today I sucked the Envirosafe out and loaded it up with 36oz of r134a. Vent temps going down the road are basically unchanged but now it's significantly worse at idle. Neat.

I'm thinking it's parallel condenser time. Dunno what else you'd do short of the complete '93 swap. I have two cheapo 10" pusher fans already.

 

[dl242gt]

A variable orifice valve made my R134 93 work decent. I also put in a new compressor that was larger and also had a larger pulley on it. It still has to run for a bit to get a handle on temps. Got the compressor from FCPEuro.

 

[Cwazywazy]

From everything I've read, plus my own past experiences, I really should be getting better cooling than I am with the r134 and I've been trying to figure it out. With the old r12 system my car's never gonna turn into a freezer, but 70f out the vent on an 82f not humid day while parked with recirc on is pathetic. I tried hosing down the condenser to chillax all the juice inside it and the vent thermometer barely moved.

Btw, it's a 1982 240 with a Sanden SD7H15 compressor, two cheap electric pusher fans in the front, stock everything else. I believe I flushed the system out with brake cleaner when I installed the compressor.

I have no high side port, which would help a lot, but the low side reports ~100psi when shut off and ~40psi idling, down to 30ish if I crack the throttle. This seems pretty normal to me, although maybe a little on the low side. I fired up the Saab to compare (also r134 converted) and that idled at 30psi low side while blowing 50 degrees out the vent. (It used to be freezing cold but it's got a leak or tired compressor or something.)

Hm, I don't really have any ideas now. The garden hose experiment says to me that a parallel condenser upgrade won't do much good if I don't figure out what else is holding it back. Could try and find a 93 parts car.

 

[go240go]

My R12 system filled with EnviroSafe runs pretty well. With the AC knob turned nearly to max cold vent temps vary between 40 and 50 F.

Prior to this I had recharged the system with R12 but it leaked out slowly. This time I redid all of the O rings before recharging with ES and also replaced the TXV, although the original one visually seemed fine inside and out. I didn’t adjust in any way, just installed the new one out of the box. New drier. Cleaned out the evaporator box under the dash, resealed with new butyl. Re-insulated the TXV with new butyl. Vacuumed the system for 24 hours.

 

[dl242gt]

I'd consider doing the a/c machine flush to the system. I've had the old expansion valve style system clog in a 240. It took using the machine to flush the system before a/c flow was restored and it worked great after that.

 

[go240go]

That’s one step I didn’t do and wished I had. Had I known the flush kit is available for loaning out at typical parts stores I would’ve.

 

[JohnLane]

From everything I've read, plus my own past experiences, I really should be getting better cooling than I am with the r134 and I've been trying to figure it out. With the old r12 system my car's never gonna turn into a freezer, but 70f out the vent on an 82f not humid day while parked with recirc on is pathetic. I tried hosing down the condenser to chillax all the juice inside it and the vent thermometer barely moved.

Btw, it's a 1982 240 with a Sanden SD7H15 compressor, two cheap electric pusher fans in the front, stock everything else. I believe I flushed the system out with brake cleaner when I installed the compressor.

I have no high side port, which would help a lot, but the low side reports ~100psi when shut off and ~40psi idling, down to 30ish if I crack the throttle. This seems pretty normal to me, although maybe a little on the low side. I fired up the Saab to compare (also r134 converted) and that idled at 30psi low side while blowing 50 degrees out the vent. (It used to be freezing cold but it's got a leak or tired compressor or something.)

Hm, I don't really have any ideas now. The garden hose experiment says to me that a parallel condenser upgrade won't do much good if I don't figure out what else is holding it back. Could try and find a 93 parts car.

Compressor is not moving enough refrigerant to get cold or the system is undercharged.
Is the high side too hot to touch out of the compressor? It should try to burn you when you touch it.
High side ambient after condenser? It should still be pretty hot if enough refrigerant is getting moved.
Your A/C should be getting to mid 40’s out the vents on recirq.
I’m betting on a weak compressor.
FWIW it is clear that the A/C systems fitted to our old junk were designed by those who live in a cold climate and don’t see the point of A/C in cars.
Sure seems like they were all fitted with an undersized compressor from the factory. Evaporator and condenser sizes seem big enough.

 

[Cwazywazy]

Your A/C should be getting to mid 40’s out the vents on recirq.
I’m betting on a weak compressor.

I drove the car 700 miles the last few days, the AC did okay on the highway sitting at 3000rpm. Pretty solid 50 degrees out the vent without recirculate. Didn't really get much colder if I turned recirc on. It still sucks butt sitting idle though, but is that because of low compressor speed or a lack of condenser airflow? The compressor is a couple years old and it wasn't a reman.

Maybe I need an overdrive crank pulley.

 

[go240go]

It sounds like you have everything you need. Like someone said above, maybe you're just a bit low on charge.

 

[Baileyswhite]

Thinking I might try closing the TXV up to like 2 turns out, from the 5-6 it's set to currently.

Did you ever do this?

On my '90 245 I frankensteined a '93 240 condenser with a r134a retrofit kit's evaporator and the TXV adjustment+consistent charge weight was what got the system to operate correctly (the retrofit kit's r134a TXV was set to something ridiculous like 15 turns out, and even adjusting to 7 turns out was too little--the high side was too high tripping the overpressure/trinary switch. I ended up at around 8 turns out after recovering and recharging the system several times).

I also installed a tropical fan clutch, a '93 240 pusher fan, a trinary switch in the filter/drier to operate the pusher fan and a digital temp controller from amazon (the exact same one dave barton cites on his A/C page) set to disengage the A/C compressor at 32°F and re-engage at 34°F vs relying on the silly stock 240 A/C knob.

It blows 47°F with recirc on regardless of ambient, and it's been installed for a year now with no change in performance.

I have no high side port, which would help a lot, but the low side reports ~100psi when shut off and ~40psi idling, down to 30ish if I crack the throttle.

It would definitely be worthwhile to add a high side port instead of guessing what's actually going on with the system running. The low side seems a little bit high (suggesting incorrect refrigerant charge or misadjusted TXV), but without a high side port we're not getting the most accurate picture.

Are you charging the system by weight or by pressure?

 

[Cwazywazy]

Did you ever do this?

On my '90 245 I frankensteined a '93 240 condenser with a r134a retrofit kit's evaporator and the TXV adjustment+consistent charge weight was what got the system to operate correctly (the retrofit kit's r134a TXV was set to something ridiculous like 15 turns out, and even adjusting to 7 turns out was too little--the high side was too high tripping the overpressure/trinary switch. I ended up at around 8 turns out after recovering and recharging the system several times).

I did mess with it a little and I switched it out for an original r12 one at ~12 turns out. As far as I can tell, the number of turns out means nothing for different txvs and the "3.5 turns out for r12 and 7 turns for r134" that people say is completely made up. I did get a made in USA r134 txv that I might try. (I forget what brand)

It blows 47°F with recirc on regardless of ambient, and it's been installed for a year now with no change in performance.

Are you charging the system by weight or by pressure?

I put in 3 cans which is 36oz, minus a tiny bit that froze my glove when I was figuring out the self sealing can thing. The Volvo service bulletins for r134 converting from back in the day all specify 1000 grams of r134 (35.2oz) for all 240s 1975-1992. None of these mention adjusting the TXV, just swapping out for an r134 unit.

Mine does the same thing where vent temps don't seem to scale with ambient temp. I guess this is an indication that the txv isn't correct? Not sure.

the silly stock 240 A/C knob.

I like the funny knob. It's neat.

 

[Baileyswhite]

I did mess with it a little and I switched it out for an original r12 one at ~12 turns out.

This adjustment is probably a bit too far out for r134a (based on your low side reading @ idle & poor cooling)--adjusting it in a few turns will give you a better pressure differential (smaller orifice = lower low side pressures = lower evaporator temperature). Again, having a high side reading would give you a much more accurate picture of what's going on (compressor health, if the TXV's sensor bulb is doing its job, etc).

Having an A/C recovery machine like you do offers a HUGE advantage because you can recover/adjust the TXV/recharge/recheck and fine tune the TXV adjustment.

As far as I can tell, the number of turns out means nothing for different txvs and the "3.5 turns out for r12 and 7 turns for r134" that people say is completely made up.

The different TXV adjustments specs are a bit arbitrary (no two systems are exactly the same, especially as these cars age and have various parts replaced/upgraded/converted/adapted) but the principle is important: R12 and R134a have different boiling points. A TXV calibrated for use with R12 will not be as effective in an R134a system.

Your car is unique and the TXV adjustment should be unique to your car, not rigidly complying with a specification in a book.

I put in 3 cans which is 36oz, minus a tiny bit that froze my glove when I was figuring out the self sealing can thing. The Volvo service bulletins for r134 converting from back in the day all specify 1000 grams of r134 (35.2oz) for all 240s 1975-1992. None of these mention adjusting the TXV, just swapping out for an r134 unit.

This sounds about right--my system ended up being charged with 2.0-2.2 lbs of R134a. It could possibly be a bit overcharged (explaining higher-than-desired low side pressure), but again, a high side reading would confirm this.

Mine does the same thing where vent temps don't seem to scale with ambient temp. I guess this is an indication that the txv isn't correct? Not sure.

By this do you mean your vent temps are consistent regardless of ambient temp? If so, the system is adapting to different conditions as it should, but suggests the TXV is out of adjustment.

I like the funny knob. It's neat.

I'm a firm believer in the "if it ain't broke don't fix it" philosophy, and I do very much appreciate a functioning stock setup. However I struggled with the knob because it's analog and therefore a bit more difficult to know what exactly it's doing. It has a very important job in the A/C system and needs to be accurate. I replaced the knob with a '91-'93 snowflake switch for a stock-ish look. And I could probably play with the on-off temps of the digital temp controller to get even better cooling without icing up the evaporator.

How have you set the knob for the tests you've performed?

 

[Cwazywazy]

How have you set the knob for the tests you've performed?

If it's hot out, anywhere past about 3 o clock it'll run continuously. I might try closing up the txv but I need another empty propane can to evacuate into.

 

[90-245]

Greetings all,

So is there an update to the initial post here? i'm going through my recently aquired 1990 245 and would like to benefit from improved efficiency! The heat gets got down here in Fl!
the vehicle was converted to r134 by previous owner, the AC comp has a "made in china" sticker on it, txv looks newish? but evap and condenser appear to be untouched.
Any part numbers for latest txv, and drier/accumulator?
I will look for a parallel flow condenser, and the recommended sanded 4664 compressor

Thanks,
Brad

 

[BlueNun301]

Wow, having just picked up a very nice '93 245. After many, many years of Volvoness...... Thank you very much. A/C is important out here in the Desert. And I hope to get it sorted. Refrigerant is tight, apparently compressor is not pushing. So, thank you very much. Have a great day !

 

[2manyturbos]

Greetings all,

So is there an update to the initial post here? i'm going through my recently aquired 1990 245 and would like to benefit from improved efficiency! The heat gets got down here in Fl!
the vehicle was converted to r134 by previous owner, the AC comp has a "made in china" sticker on it, txv looks newish? but evap and condenser appear to be untouched.
Any part numbers for latest txv, and drier/accumulator?
I will look for a parallel flow condenser, and the recommended sanded 4664 compressor

Thanks,
Brad

If your AC is already working start by replacing the refrigerant with Envirosafe. It gets much colder than R-134.

https://autorefrigerants.com/enviro-safe-refrigerants-and-accompanying-products/

 

[Cwazywazy]

From everything I've read, plus my own past experiences, I really should be getting better cooling than I am with the r134 and I've been trying to figure it out. With the old r12 system my car's never gonna turn into a freezer, but 70f out the vent on an 82f not humid day while parked with recirc on is pathetic.

Good news! I got the AC up and running today on 36oz of r134 and it's blowing colder than ever!

Last year, about a month after I charged it with r134, the compressor to condenser hose blew out behind the grill and showered my windshield with pag oil. I'm just now realizing that I should've added more oil. Oops.

Anyway, I swapped out the TXV for a new made in USA r134 unit from the dealership and a new hose. Now at 82f outside I'm seeing 50 at the vent while parked and damn near 40 going down the highway with the knob turned all the way up. Previously, in similar weather, I was seeing 70 parked and it would eventually creep down to 50 on the highway. The best part is I haven't put the condenser fans back in, this result is with just the main radiator fan on low speed.

 

[bobxyz]

The 240 condenser fan turns on when the high-side (pre orifice tube) pressure goes too high. Unlike the 740/940s, over pressure will NOT turn off the compressor. Beware, you may hit over pressure when sitting at stop lights.