A/C Gauge Readings

[clinebarger]

I checked it again with the gauges and this is what it shows. It was roughly 30-33 and 150-160 before going to the shop.
View attachment 226076

Does this mean I need to evacuate it before recharging?

Either you created a leak at the service ports or the shop stole your refrigerant, Common practice unfortunately in the pursuit to sell a job.

I replace many Honda/Acura compressors for clutch failures & performance issues in the flow control system, Rarely is anything else needed.
Oil balance is important in such a small system, Change the Shrader's, Deep vacuum the system & charge by weight.

 

[Snagglefoot]

I’ve seen those charts that suggest what the pressure should be at various ambient temperature, but haven’t noticed a suggestion as to the rpm to use. What’s the correct answer?

 

[Snagglefoot]

How does one deal with what to do regarding the amount of lubricant in the system when drawing down a system with the vacuum machine?

 

[Nukeman7]

I’ve seen those charts that suggest what the pressure should be at various ambient temperature, but haven’t noticed a suggestion as to the rpm to use. What’s the correct answer?

Per Nissens, pressures should be taken with the engine warmed up, A/C controls set to max., RPM at idle with the compressor clutch engaged.

NISSENS AC Pressure Readings

How does one deal with what to do regarding the amount of lubricant in the system when drawing down a system with the vacuum machine?

Personally, I wait a few hours or overnight before pulling a vacuum on the system and have never observed any amount of oil removed from the system. I have only added oil when replacing components.

I use a simple Robinair 6 cfm vacuum pump, but the professional refrigerant recovery machines contain an oil separation filtration system that collects and measures any removed oil in a cup (see below).

 

[tiger862]

I checked it again with the gauges and this is what it shows. It was roughly 30-33 and 150-160 before going to the shop.
View attachment 226076

Does this mean I need to evacuate it before recharging?

I hate shops like that. They still believe in r12 mess which states if a customer comes in with a leak Evacuate. Once Evacuated whole system replacement is only option. Customers get vehicle back empty and with heat they gladly pay.

 

[Jango]

Per Nissens, pressures should be taken with the engine warmed up, A/C controls set to max., RPM at idle with the compressor clutch engaged.

NISSENS AC Pressure Readings


Personally, I wait a few hours or overnight before pulling a vacuum on the system and have never observed any amount of oil removed from the system. I have only added oil when replacing components.

I use a simple Robinair 6 cfm vacuum pump, but the professional refrigerant recovery machines contain an oil separation filtration system that collects and measures any removed oil in a cup (see below).

If the shop evacuated my system of the R134, would that remove the oil too? How do I determine if I need to add some or not?

 

[KJSmith]

Typically evacuating a system does not remove oil.
You evacuate to remove air/impurities and moisture.

If the system had/has a leak, you would lose oil at that point.

 

[Jango]

In using a vacuum pump, what are the rules of thumb for how many minutes to leave the pump on and how long to wait after turning it off to determine if it is leaking?

 

[Donald]

If wife rides in the vehicle get it repaired. If it's a beater toss in a can of R134a as needed.

Remember the proper way is to pull (and check if it holds) a vacuum for 30 min? Then fill by weight.

You could bring it to a shop, have them remove the R134a then you replace all the o-rings and Schrader valves and then bring it back for them to pull a vacuum and see if it holds. O-rings and Schrader valves are the likely inexpensive items that could cause a leak.

 

[Nukeman7]

In using a vacuum pump, what are the rules of thumb for how many minutes to leave the pump on and how long to wait after turning it off to determine if it is leaking?

It varies depending on how long the system was opened to atmosphere (i.e., how much moist air infiltrated the system) and how dry the air is. As a rule of thumb, I always vacuum the system down to approximately -30 in.Hg for 20 mins. and secure valves/pump to check for leakage over the next 15-20 minutes. If no loss of vacuum, I'll pump it down for another 40 minutes for a total of 1 hour under vacuum. Here is a decent video you should watch before attempting the repair.

 

[Jango]

I ran the vacuum and it held pressure. I added the appropriate amount of r134 and the ac gets down to about 43 degrees. However, after awhile the ac stops cooling. Any ideas what is causing this to happen?

 

[Jango]

I watched a bunch of videos and found out that on many older Honda`s the issue is a bad ac clutch. A fix is to remove the clutch and remove a shim in between the clutch and the rotor pulley. This reduces the air gap to the field coil.

I gave it a shot and my ac is working great. I test drove it an hour when it was 109 F out. It gets down to around 40 F. Such a simple and easy fix.

 

[KJSmith]

I had a F250 for about 9 years.
Bought it new.
At one point my clutch wouldnt engage.
You could bump it with a stck and it would work.

A mechanic buddy told me to remove the front plate and clean the rust off everything.

Worked like a champ after that.