Flushing the evap

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iXod
Posts: 4
Joined: Wed Apr 19, 2017 11:58 am

Flushing the evap

Postby iXod » Wed Jul 10, 2019 8:50 pm

2004 Mazda 3 R134a system wouldn't cool. Gauges show low side going into vacuum. Obvious txv plugged. Suspected grenaded compressor so examined a little oil from the system and it's dark. No particles but that doesn't give me any hope.

Will replace all major components: comp, cond, dryer, valve, and flush all lines and evap.

My question is about flushing the evap. It uses a block type txv which bolts to the evap deep in the dash. How do you flush it? Can't flush with txv installed (which would give convenient lines under the hood to connect flush equipment). Without txv connected, there are just 2 holes in the air box that lead to the evap:

https://imgur.com/MSOEgDW

How do I flush the evap without contaminating the whole passenger compartment?

Thanks for your help.

iX
pete_89t2
Posts: 21
Joined: Thu May 04, 2017 9:38 am

Re: Flushing the evap

Postby pete_89t2 » Thu Nov 05, 2020 4:25 pm

It should be possible to remove the whole evaporator core & TXV as a unit from the dash. Do you have a factory shop manual for your 3? Once it's out, you can remove the TXV and flush the evap core by itself. That's the general way to do it, and how I flushed my evaporator core when I restored the A/C on my '93 Mazda RX7 - it has a similar block type TXV, so flushing in place wasn't an option. All in all not too hard to do. I had to remove the glove box door, and some interior trim bits, disconnect the H/L lines into the core from the other side of the firewall. Then it was a as simple as unplugging a couple of electrical connectors that were in the way, and 3 nuts securing the evap. core unit to some studs on the firewall.

It's wise to take a few pictures as you remove things, as there's usually a bit of origami like maneuvering and excessive swearing necessary to get it back in the same way it came out.

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