Selecting a condenser for a custom AC installation in a '93 Mazda RX7

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pete_89t2
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Selecting a condenser for a custom AC installation in a '93 Mazda RX7

Postby pete_89t2 » Tue Nov 12, 2019 10:25 am

Greetings,
I'm about to acquire a modified '93 Mazda RX7 project car that I'd like to restore functional AC to, and can use some advice. As it sits right now, everything AC wise on the interior side of the firewall (e.g., evaporator core, expansion valve and HVAC blower/air handler unit & HVAC controls) is intact. What's missing is the stuff on the engine side of the firewall - compressor, condenser, receiver/dryer and all the AC hoses & hard lines required to plumb it all together.

I found that sourcing & reinstalling a reman/new OEM compressor for this car will be a simple bolt-on affair, but because the engine bay has some extensive mods (big turbo, larger AL radiator, front mount turbo inter-cooler) simply finding a new/used OEM condenser and OEM hoses/hard lines from a donor car won't work.

Plan is to convert to R134 refrigerant (original was R12), and let's assume I can find a suitable place to mount the condenser so it has sufficient airflow thru it (not a trivial problem, but it can be done with some re-packaging of the car's radiator & IC setup). Given these assumptions, my questions are:

1. How large of a generic parallel flow condenser will I need (core length X width X depth) to get good cooling performance with R134?
2. For the expansion valve, will the original valve (which I presume was designed/calibrated for R12) work with R134, or should I be looking for an R134 version from a later model RX7? (they sold in Japan & elsewhere thru 2002)

Thanks!
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Tim
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Re: Selecting a condenser for a custom AC installation in a '93 Mazda RX7

Postby Tim » Tue Nov 12, 2019 5:03 pm

Proper cooling in general. 14 x 24 PF condenser is needed.

Exp valve reads temp at the probe. R12 or R134a.
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pete_89t2
Posts: 13
Joined: Thu May 04, 2017 9:38 am

Re: Selecting a condenser for a custom AC installation in a '93 Mazda RX7

Postby pete_89t2 » Wed Nov 13, 2019 6:58 am

Tim wrote:Proper cooling in general. 14 x 24 PF condenser is needed.

Exp valve reads temp at the probe. R12 or R134a.


Thanks! Being a bit of an AC noob, with regards to the condenser, should I be selecting based on a minimum surface area? So at the recommended 14 x 24 size = 336 square inches, would a different L x W condenser work as long as it's > or = 336 square inches? Just trying to give myself more flexibility in packaging this thing.
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Tim
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Re: Selecting a condenser for a custom AC installation in a '93 Mazda RX7

Postby Tim » Wed Nov 13, 2019 7:12 am

The largest condenser possible depending on the available area.
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