Expert: Howard Livingston - 7/4/2009

Question
QUESTION: I have a 1976 Coleman rooftop AC unit on my Motorhome, It runs OK, not the coldest, but after a short period it kicks into thermal overload I think. I cleaned the coils & it seemed to run longer especially in the AM when the temp was cooler. Do you think it is the capacitior or what?

ANSWER: 33 years old  !!!!   They made good stuff then. Not anymore.
Fan motors is the favorite thing to fail. But it could be low on freon & the compressor gets hot & kicks the breaker. Or it could be the bearings on the compressor are worn (after 33 yrs) & thats the problem. That kind of problem could best be found putting gauges on it & watch it till it fails.

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QUESTION: How can I add or convert the freon

Answer
sually there is not a service valve on those things. But you can buy a clamp made for the diameter of the suction line that will provide a connection for a gauge. That age stuff may even have R 12 in it. Check the nameplate. R22 can be found in auto supply stores but expensive but if it is low, convert it to a "drop in" ref like Hot Shot