Heater exhaust to close to AC unit?

[Caylumo]

I have heard several times that this is ok and several times that it is not. What is the issue? The furnace exhaust is approx 9 inches from AC unit.

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[Tom Raymond]

Most manufacturers specify a minimum clear space around the exhaust to minimize draft issues that could shut the furnace down.

Also the exhaust contains acidic condensate that will corrode the condenser.

Bad for furnace, bad for condenser, bad for anyone that says it's ok.