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Cargo and flight station A/C seem to have same problem


chickenstrip76
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We have an R model with flight station and cargo a/c problems. The a/c is running full hot, no matter the setting. We have checked out the control box, and the temp control valve, both are working fine. When selected to hot, the temp control valve opens, when selcted to cold, it closes, so these are not the issues. I was wondering could it be 2 failed anit-ice valves? I was messing with the a/c anti-ice control panel with power on. The "open" lights both work. But, when I move the switch to the "open" position, the "open" light does not illuminate. Both gripes showed up a day apart. The aircraft was on det, and the flight station went out. The next day, cargo did the same. I need help!

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When you say "No matter the setting" I ASSUME you mean in AUTO and the setting is with the rheostat knob..

Do the AC units go full HOT in Man?

"R" model with anti-ice? Only four of those aircraft that I remember... anti ice was for the intake and did not interface with temp control...

Take the cannon plugs off the Temp control box and "jump" B to E and C to F; that will give direct control to the FE. The manual temp select switch will directly control the temp control valve. No duct protection is avalible so caution is the needed...

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A/C went full hot in man and auto. Its looking like we have 3 failed valves. All the same part number, just used in different places. Flight and cargo run hot, and underfloor heat temp does not regulate, and to quote the aircrew write up, "Simulates the surface of the sun". Just seems weird that all three valves would fail in a short period of time.

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I think only two of them are the same.... the underfloor heat is different...it divertes more or less HOT air not mix cooled air and warmed air.... and both (or all three) valves bad with the same issue full hot....

The valves only do what they are told to do. In Manual there is nothing to drive the valve except to cold. The butterfly (inside) may not be closing but it soulds like it is in manual.

In auto you may have a bad duct anticipator that should limit the speed in which the valve can move to full hot.

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