Rebuilding AC evaporator assembly

501 Views 15 Replies 4 Participants Last post by c900, 1 mo ago

c900

For my 1990 9000 carlsson, The Ac evap has been out of the car for 7 yrs and it's time to sort that out and get the climate stuff functioning. I've got a new aftermarket (OEM new unobtainable) correct part number AC evap unit and I'm having trouble getting the two parts of the plastic housing to fit together properly on the end where the pipes come up through the lid.

I've double-checked and the evap unit is slotted into place correctly. Sadly my flickr acct got deleted (NFI why) so I can't link up any pics but the only possibility I can come up with is that the piping matrix at the fitting end is a bit different in how all the tubes are joined and may be pressing on the top bit of the housing when it's pushed down.

I'll be a bit more 'pushy' and see if it will go, but I'm mindful that the OEM original one (very dead) had the pipework done somewhat differently.

The Evap unit is Saab 96 24 925. There's one currently on Ebay that looks identical to the new oldstock aftermarket one I'm fitting up now:

Saab 9000 1986 1987 1988 1989 1990 1991 NEW AC Evaporator Core EV 5909ATC | eBay

Find many great new & used options and get the best deals for Saab 9000 1986 1987 1988 1989 1990 1991 NEW AC Evaporator Core EV 5909ATC at the best online prices at eBay! Free shipping for many products!

www.ebay.com

I've found that I need to actually modify (slightly) the opening in the top cover of the evap housing and bend slightly the 'flange' on the end of the evap unit that fits into the slots in the housing. Simple job with some pliers (for the metal flange) and files (for the plastic of the top cover) and all is going together well.

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c900

Discussion Starter · #2 · 3 mo ago

Woo hoo pics are back. https://flic.kr/p/2on1Ny6
https://flic.kr/p/2on4msK
I'm working on the external bits now - inserting the defrost thermo-contact (don't have a new one of those) etc. Mostly new oldstock bits overall.

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c900

Discussion Starter · #3 · 3 mo ago

Defrost thermocontact and sensor probe re-fitted.

https://flic.kr/p/2oneqTQ
Had to take out the rubber grommet to see where to place the sensor probe.

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c900

Discussion Starter · #5 · 3 mo ago

I didn't have anything come apart unexpectedly. I'm not sure what you mean by 'retaining plate'.

one question - the thermo-coil for the TX valve. Is that supposed to be clipped to the pipe of the evap core or does it sit freely in the air path coming from the blower fan? It's the one thing I don't remember since taking the evap assy out of the car about 7 yrs ago and pulling it all apart.

https://flic.kr/p/2oo2EeJ

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c900

Discussion Starter · #8 · 2 mo ago

I found a stainless steel spring-clip that I think was used with the original TX valve to secure that small coil against the large pipe. Hadn't realised what it was for at first. Now I just need to work what sort of goop to close in the openings in the housing where the evap core pipes come through as the original goopy foam stuff is no good after 33 yrs.

I've got a tube of D-mastic but not sure that's quite appropriate.

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c900

Discussion Starter · #10 · 2 mo ago

I've opted for a tube of neutral-cure roof and gutter sealant as that's what the local hardware store has available since it's used for exterior roofing work. I went for grey instead of black so it's easier to see when applying.

As for the TX valve, I modded the original clip slightly to hold the thermo-bulb on the pipe from the evap core as the pipe is bigger OD than on the Saab original one. No big deal - I've got the thermo-bulb in place now.

https://flic.kr/p/2or4p44
I'm going to use a product called Nylog blue to help all the new green o-rings seal up well - can probably fit everything up without using the Nylog but it's been recommended by a few people who work on building and car HVAC's for their jobs. There's a Nylog red but that's a different compound. Should I not use anything with the o-rings? Doesn't hurt to ask.

Once I am happy with the evap unit I'll try to re-install it and the already rebuild cabin fan unit. BTW I am considering replacing the volvo bullet connectors for the fan unit with Deutsch DT ones (the 25 amp rated version) and maybe some of the other elec fittings as the other Volvo bullet connectors didn't all come apart nicely.

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c900

Discussion Starter · #12 · 2 mo ago

Ok there is only one part I was not able to get as a new old-stock item - 96 27 159 the AC trinary pressure switch. There is a Valeo part that crossed over to the Saab part number but is has a different connector and the end that secures to the receiver/dryer does not match up (totally different thread configuration). This is the original factory part from my evap assy

https://flic.kr/p/2or5nmt
Does anyone know what a matching aftermarket part might be? Don't worry about the connector as I'll probably go to 4-pin Deutsch DT style anyway.

There is a Jayair part that shows as a match to the part number but it's the same as the Valeo one with a totally different thread config.

I see there are loads of generic ones showing the right thread spec on Ebay from the USA though.

I'll re-use the one I have for now and hope it still works ok.

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c900

Discussion Starter · #13 · 1 mo ago

Today I have re-installed the rebuilt AC evap assembly into the car after removing it probably 7 years ago. I've been able to work out where all the wiring goes except I don't remember which two contacts on the defroster sensor it's two wires go onto? Does anyone know or have a pic?

I still can't locate an AC trinary switch but have re-installed the original one for now. Can anyone say if the aftermarket ones with the same thread spec can be made to work with their connector changed?

With the AC evap unit back in, next step is re-fitting the rebuilt cabin fan unit that has also been out of the car for the past 7 ish years. It was rebuilt about a year ago and has been waiting...

The car is also back on the ground with the front end work on the coolant system, etc. basically completed so it's easier to work on the climate control stuff.

https://flic.kr/p/2ovVbtw

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c900

Discussion Starter · #15 · 1 mo ago

Not really - AC is a snobby privilege if you want my honest opinion.

I actually am removing AC from my 2.1 c900 sedan, and my other c900's all had AC not working or I removed it. My 81 turbo sedan that hasn't been a runner for about 5 yrs had AC taken out very early on after I got it probably 15 yrs ago now. But the 9000 is more of a classic prestige car and I hunted for a few years to get all the parts, so fingers crossed it'll get functional again and as it has ACC 2.0 that's supposed to be a good system when it functions properly.

My other vehicle is a diesel 4wd that I've owned since 2011 and it has never had AC working in that time.

It's windows down for AC baby... A heater for the cool weather is far more important than AC in my view.

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c900

Discussion Starter · #16 · 1 mo ago

I've been working on the false firewall panel today - made some new foam bits for the coolant and vacuum hoses that pass through it.

However when I've tried to install the panel proper I find it's interfering with the main pipe to the AC evaporator core. The pipe is the original one so was used with the old core that got replaced, but I'm guessing the forming of the pipework isn't exactly identical.

I need to shift the pipe back towards the main body of the car probably 5 mm to give enough clearance or I have to force the false firewall panel to bend slightly where it isn't supposed to.

Has anyone else encountered a similar situation? Here's a pic.

https://flic.kr/p/2ow6k2u
Being as the core is made from copper piping if I just push on it enough to slightly bend it that might be ok.

The false firewall btw had a full repaint with POR-15 some years ago and has been stored away waiting for the day it would go back into the car.

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