Engine Size: 1.8L
Refrigerant Type: R-134a
Ambient Temp: 90
Pressure Low: ???
Pressure High: ???
Country of Origin: United States
On my 94 Corolla with the factory sight glass, it's clear at idle - when I take it to 2,000 rpm with A/C on full blast it's still clear with an occasional little burst of foam, and when the electric fans switch to high, it instantly gets foamy and clears. When I let it back to idle, it will have another big burst of complete foam and then clear. Vent temps are 60 degrees.
Edited: Sun August 03, 2008 at 6:20 PM by Drew99GT
It's also clear if the compressor is not running, is the compressor running at 2,000 rpm, blower at max, doors open, AC on? Or is it stopping when the fans switch on?
Take a can of black paint and paint the sight glass so you cant see in it. It's useless with R134a.
Factory R134a systems with site glasses can be used, it's retrofitted systems that you can't use the sight glass. Recover and recharge the factory amount back in, then use the sight glass to check.. But you do need the full charge in the system..
Freedoms just another word for nothing left to lose
Sight glass is very reliable for determining the state of charge, even testing for leaks if more bubbles start appearing a couple of weeks later under the same ambient conditions.
But this is in a normally operating system, yours is not, could be a plugged up receiver or a TXV slowing down the rate of refrigerant flow where the only way to find out is with manifold gauges.
Also, a very common overlooked detail that is extremely important for good performance as well as correct pressure and sight glass readings, is a clean system with all fans working properly! Remove your blower motor so you can view your evaporator face and tell me what you find. I don't even want to tell you what I have found, but amazing that any air could pass through it. Least a little. Without proper air flow, the expansion valve will close tight dripping refrigerant into the evaporator, that really accounts for warm vent temperatures, even if everything else is right.
Chris makes a good point.
The condition you're describing could be entirely normal. R-134a systems do foam. Toyota differentiates between foaming and bubbling (foaming is the result of the oil on R-134a systems). Foaming can also be an indication of the receiver dryer desiccant has broken down, or excess oil on R-134a systems?
Toyota FSM instructs the technician to "charge the proper amount of refrigerant into the charging cylinder" and also to check pressures. What are the low and high side pressures on this system so we can all stop guessing?
Don't know pressures - I don't have guages. I'm just gonna suck it up and have a mobile A/C guy come evac and recharge the factory amount of 134a and I'll report back.
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