THIS UNIT HAD A LEAK IN THE SEALED SYSTEM. I REPAIRED THE LEAK REPLACED THE FILTER DRYER, VACUUMED DOWN AND RECHARGED THE SYSTEM. THE UNIT IS COOLING WELL. THE FROST PATTERN, ON THE EVAPORATOR COIL, IS NOT EVEN. THE LOWER PORTION HAS FROST AND THE UPPER HALF DOESN’T HAVE ANY FROST. AS I SAID IT IS COOLING WELL BUT IS RUNNING AT 20inHg vacuum. TYPICALLY, WHEN I SEE THIS LOW PRESSURE THE UNIT WON’T WORK AT ALL. DO YOU HAVE ANY INSIGHT AS TO WHY THIS IS RUNNING AT SUCH A LOW PRESSURE? IS THIS INDICATIVE OF ANOTHER ISSUE WITH THE COMPRESSOR?
THANKS
- Guest asked 8 years ago
Hello
If you are running a -20 vacuum and a half frosted evaporator you have a low refrigerant charge. The evaporator is starved for refrigerant. This should be running 2-4 lbs suction pressure in a 70 degree ambient temperature. Bring the charge up to 2-4 lbs and you will find a frosted coil top to bottom. Matt Ace technician
- AV Repair Help answered 8 years ago
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I WEIGHED IN THE CHARGE ACCORDING TO THE DATA PLATE, 5oz. THE PRESSURE WAS LOW SO ADDED ANOTHER .6 oz. THIS DIDN’T HAVE ANY SIGNIFICANT EFFECT ON THE PRESSURE. THAT WAS WHAT MADE QUESTION IF THERE WAS ANOTHER ISSUE WITH THE UNIT.
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You have one or two possibilities. you still have a low refrigerant charge. Or the second is a restricted capillary tube or filter drier. When you did the brazing did you replace the filter dryer? If you did you may have the capillary tube partially plug which would cause the unit to go into a restriction and a starved evaporator only half frosted.
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WHEN I REPLACED THE FILTER DRYER, I BRAZED ONE END ON THEN CHARGED THE SYSTEM WITH NITROGEN TO MAKE SURE THE CAPILLARY TUBE WAS CLEAR. THE CAPILLARY TUBE HAD NITROGEN COMING OUT OF IT. THEN I FINISHED BRAZING AND CHARGED THE SYSTEM. I JUST WENT AND ADDED GAS TO THE UNIT TO BRING THE PRESSURE UP. I ADDED ANOTHER 4.4 oz OF 134A. THIS IS A TOTAL OF 10 oz, DOUBLE THE FACTORY CHARGE AND IT’S STILL RUNNING AT 10 inHg VACUUM. SO YOU THINK I HAVE A BLOCKAGE SOMEWHERE OR PERHAPS A PARTIAL BLOCKAGE OF THE CAP TUBE, AS IT’S HARD TO SAY IF THE GAS COMING OUT OF IT WAS THE PROPER VOLUME?
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