AC not very cold

[AlexO]

Hello,
I’m trying to figure out why my AC is only cool but not cold.
The condenser is in good shape, fans turn on and clutch engages.

I was thinking of adding some refrigerant but wanted to run it by someone more knowledgeable in this before I do that.

I ran the car for 10-15 minutes in 85 degree weather (AC on Max) and get 25 psi on the low and 155 psi on the high.

Are these pressures normal?

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[acurax]

So, having been down the road of adding refrigerant myself in that past I think more diagnostics are needed.

You'll want to confirm the A/C clutch engages and look for any unusual frost areas, i.e. on or around the a/c lines and components.

If all appears good, then you can move on to the temp and pressures. Since you've already taken a pressure reading, I'll post those images first. These are all for the non-Type-S since your profile indicates you have an A-Spec, but if that's incorrect I can swap these for the Type-S graphs.

Use the graphs to determine what the correct high low ranges are based on your outside temperature.

If that all checks out, then you could check the air temp entering and exiting the system against this graph.

If the temps are not within the correct range based on the graph above, then it's likely best to have it checked at a dealer, if under warranty, or a trusted shop. They should be able to safely measure the volume of the refrigerant which would decisively tell you if there is a leak. If the volume is below spec, they can then do a leak test to find it and tell you exactly what needs to be replaced to fix it. You can still decide to just pump refrigerant in as it gets low, but it's possible to put too much in which will have the similar result as not having enough.

 

[AlexO]

Thank you for the graphs, and yes, I have the A-Spec.

According to the graphs, the low is just barely within spec and the high is low.
Sounds like I just need add just a bit of refrigerant.

As far as other components, clutch engages and no frost build up on the lines or condenser.

If there was a leak in the system, would I see the pressure drop in the 10 minutes I ran the AC?
I monitored the pressure while it was running and it stayed stable.

I'll check the pressures again this weekend. If they remain the same, is it safe to say that it's not leaking?

 

[acurax]

Well, it's possible that when things move around a small amount leaks out through a connection somewhere which may compound over time, but not significantly enough to see a measured change over the short term.

 

[Frenzal]

The leak can be very small and takes days or weeks...

Been there, done that, but on my TLX.

 

[Gremlin85]

Most common leak point in almost all systems are the shrader valves at the ports. Usually just evac the system, replace valves, refill to proper amount, and it should be good for more years to come.

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