Hi Guys,

My a/c is blowing hot air; low pressure port is ok (40psi), but my high pressure port has 0 pressure (should be over 150)
I put 3 cans of 134a last week: system worked fine couple days.
Can any body help me.

guzman_marcos@yahoo.com

 

It is not possible to have 40 psi on one port and zero pressure on the other.

When the system has not been in use for a while (more than 15-30 minutes), the pressure equalizes through-out the system.

The cycling switch requires aminimum of 43.5 psi to close and to enable the compressor clutch. If you have less than that pressure, the clutch cannot be energized.

As for the zero high-side reading, double-check your manifold guage set or check the high-side test port for a malfunction.

If that 40 psi low side reading was correct, your system is low on charge. This means you have a significant leak that must be repaired.

Steve

 

Hi Steve,

Events: about 10 days ago; vacuumed the system for about 30 minutes, then charged with oil and 3 1/2 cans of 134a: a/c worked fine for two days and then started blowing hot air.

why did the vacuum? had small leak near the low port of compressor which got it fix.

Do you think that I should charge one more can of 134a?

Do you have an schematic of this system?

Do I have a filter (maybe clogged)?

I think I have a restriction somewhere in the system, maybe debris I guess after vacuuming.

regards, Marcos

 

Steve,

I don't see what point 3 psi is going to make when having zero high side pressure, correct? I surprised the system is not
pulling into a vacuum. it sounds like a restriction but I may have a totally different problem.

regards,

Marcos

 

I have to repeat my first sentence above. It is not possible for such different readings to exist. Period. In a system at rest, the pressure HAS to be equal everywhere. It is only when the compressor runs that the low side drops and the high side rises.

As I also pointed out, the clutch CANNOT engage unless there is a minimum of 43.5 PSI in the system. You only have 40 indicated so the clutch cannot energize.

Even if there is a restriction/blockage, it doesn't matter. The clutch cannot energize given the conditions you reported.

Please review your A/C troubleshooting fundamentals and practices.

My guess is you still have a leak that needs to be repaired.

Yes, I have the schematic. It is included in the service CD.

Steve

 

Steve,

dont have the schematic

could you send me the drawing by e-mail?

guzman_marcos@yahoo.com

I was checking the a/c a while ago; now in the high pressure por I get 100psi, I think I got a a leak In the expansion valve in the back of the vehicle.

regards,

Marcos

 

Sounds like you got a leak if your high side is only 100psi.
I would get a black light and check all your hoses and compressor, accumulator, and condenser. You definitely have a leak somewhere


FordMasterTech