Quote:
Originally Posted by ganun
Simple answer is yes, but it's due to running with somewhat undercharge which achieves dual functions. One is to get a cold evap, and two is to provide hi side head room, i.e. keep hi pressure from going too hi if in heavy traffic for example.
Ideally one would charge enough so that low side pressure corresponds to just over 32F, but with the 911 system that would put the hi into the too much pressure, definitely over if caught in traffic.
The down side of the undercharging setup is monitoring temps, since like I said before there is no climate control computer.
Around town on normal traffic this is no problem, there is no freeze up, but on the hiway it will freeze up after an hr or so if you don't realize vent is in the 30s and you don't turn up the thermostat.
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So you're saying that a person can purposely under fill the system in order to get lower evaporator core temperatures than the system, TXV, etc, would otherwise allow..??
But, as you say, and I agree, on the "flip" side of that one would need to pay reasonably close attention to the vent temperatures and raise the cooling setpoint should those indicate an impending freeze-up.
1. The "claimants" contend that no such adjustment is required, which I could understand in DRY climates, but "these" are well known to be oftentimes relatively, even extremely, high Rh climatic areas.
2. In any case shouldn't, wouldn't, a properly installed and calibrated T-stat accomplish exactly that? Disregarding, for the moment, the fin spacing issue.
With the above criteria met the evaporator core would not decline enough to trigger the opening of the compressor clutch circuit unless/until the cabin atmosphere had reached the top end of the Delta "T" span, the incoming air to the evaporator core is low enough that the system can/will/could/might lower the outflow into the danger zone, freeze up imminently pending.
So, working properly, as designed, fully charged with refrigerant, you would have SUPER cooling of the cabin right up to the point of impending evaporator core freeze up.
If not, what am I missing?