Designing A/C System Using Other Cars Parts?

[HusseinHolland]

Took the dash out today, to deal with the aftermarket AC work

Yuk - 48 years of dust & dirt

Dash is actually easy to remove - entire harness unplugs on the pass side, and then just a few connections on the left side of dash. I found it to be very heavy though! I also flushed all the ductwork and tubing, however I'm going to put new tubing in. No way to get all the kaka out of the old ones, and I don't want to be blowing all that crud into the cabin. New dash will go in after all this

After several go arounds with sponge, soap & water

 

more yuk

made a left side support bracket for the housing plate - the whole thing was hanging off the right ear

Evaporator has flare fittings. I've order a #8 & #10 straight flare, and a #8 to #6 step barb

Tried fitting the existing hoses to see if I can cut them down - they only need to go to the bulkhead, but the #10 has a 90º elbow, so the routing is very untidy, and the #6 goes to the (now hollowed out) expansion valve, but it's still unwieldy so I'll just make new ones with cleaner routing

 

I found these were mounted under the hVAC control panel - added to control the aftermarket AC thermostat & fan(?) The left one responds to fan position, the right responds to temp setting . I don't have a wiring diagram, so I'm not sure why they added them, honestly.

[Dave WM]

interesting, not a factory evaporator, looks larger, maybe it cooled better? But then again the larger part was out of the air flow and looks like only two rows iirc, factory was 3 maybe 4.  Looking forward to see what you come up with. My 2 cents would be some way of pushing more air thru the ducts, in addition to cooling from the evap.

[HusseinHolland]

19 hours ago, Dave WM said:

interesting, not a factory evaporator, looks larger, maybe it cooled better? But then again the larger part was out of the air flow and looks like only two rows iirc, factory was 3 maybe 4.  Looking forward to see what you come up with. My 2 cents would be some way of pushing more air thru the ducts, in addition to cooling from the evap.

I was wondering how it compared to factory.  It's 14"x3"x4" -so 168 cu. In.

[Captain Obvious]

21 hours ago, HusseinHolland said:

I found these were mounted under the hVAC control panel -  I'm not sure why they added them, honestly.

I assume the switch responding to the fan position disables the A/C it the fan is in the off position (so you don't slug the compressor). And the other switch probably cycles the compressor based on the temp of the air through the evaporator.

I'm pretty sure you knew all that already, so I guess I'm not sure what the question was?

[HusseinHolland]

35 minutes ago, Captain Obvious said:

I assume the switch responding to the fan position disables the A/C it the fan is in the off position (so you don't slug the compressor). And the other switch probably cycles the compressor based on the temp of the air through the evaporator.

I'm pretty sure you knew all that already, so I guess I'm not sure what the question was?

Yeah, it just would make more sense to have a switch that turned the (blower) fan on with AC engagement, rather than one than disables the AC thermostat if it's NOT on. 

Do you know if the fan speed resistor is different for AC models? I'm wondering if it's worth playing with differing fan speeds than provided.

[Captain Obvious]

18 minutes ago, HusseinHolland said:

Do you know if the fan speed resistor is different for AC models? I'm wondering if it's worth playing with differing fan speeds than provided.

Yes, the resistor is different. You see.....

The non-A/C cars (like yours) have three fan speeds while the A/C equipped cars came with FOUR fan speeds:

But the top speed bypasses the resistor in both cases so the highest speed is the same.

Point is... Yes, the resistors are different, but really doesn't matter for what you're doing.

[Captain Obvious]

Thinking about it for another second though, there is one detail that bears mention...

The "Fan is not in the OFF position" signal is built into the four speed switch that came with the A/C cars. Since your car did not come with A/C and has the three speed switch, you need that auxiliary aftermarket installed switch.

Here's a couple pics of the four speed switch:

[HusseinHolland]

11 minutes ago, Captain Obvious said:

Thinking about it for another second though, there is one detail that bears mention...

The "Fan is not in the OFF position" signal is built into the four speed switch that came with the A/C cars. Since your car did not come with A/C and has the three speed switch, you need that auxiliary aftermarket installed switch.

Here's a couple pics of the four speed switch:

That makes more sense. Any chance you have an extra 4 speed switch? 🙂

[Captain Obvious]

I will take a look to see if I have one of those switches.

If not, I'm assuming the aftermarket add-on you have installed (functionally) does the same thing?  What the stock switch does is connects the blue/white to ground any time the switch is in any position other than OFF. Your switch may not do the exact same thing electrically, but functionally within the system, it should serve the same function (to turn the compressor off unless the fan is spinning).

[HusseinHolland]

I actually want the 4 speed fan option 🙂 - the after market cut off switch I would then eliminate. The fan I will wire to run at lowest speed when the AC is engaged, like my X1/9 

I'm also going to add the delay relay (E, #1363449) that Volvo used in the 80's, prevents the AC running until the alternator is charging. This model also used the same thermostat switch (B) as the aftermarket setup so I will incorporate that 

[HusseinHolland]

 

Worked on the AC hose routing & accumulator placement today. The bulkhead fitting was the wrong size, so I had to cut it & add a center section to space it out, used the factory cover plate as the template

after welding, cleanup & paint, adding a closed cell foam seal

determined the most suitable location for the accumulator. This will likely need revision when the drivetrain swap happens

high side hose routing, with orifice tube & trinary switch

crimped the line fittings

Made the (Volvo) accumulator mount bracket work - modded the brake master heat shield (from a '78) to accept the accumulator bracket

Low side hose goes from #12 fitting to #10 line. This is I made years back for the X1/9/Honda setup

Made sure throttle link clears the AC hose throughout it's arc of travel

bracket needs another support here to prevent unwanted flexing

Have to cut up the compressor bracket & rework with Volvo rubber mount isolated ears

 

[HusseinHolland]

Made the additional support bracket for the heat shield, to account for the additional weight of the accumulator & hoses

After that I got started on the AC compressor mounting

Datsun compressor on top in stock offset position - I want the new compressor to sit back& use the outer pulley, so I set the new compressor on the inside of the existing bracket to compare offset

The belt won't align as is - so I have to move the compressor forward just about a 1/4" inch. That meant I had to cut off the existing bracketry & only made use of the back plate aspect

tack welded the Volvo bushing mounts, checking alignment as I went 

4 of the five in place - the last I need to have to compressor mounted on new bushings before I weld that one in place

Edited August 15, 2023 by HusseinHolland