Air Conditioning Service & Maintenance

Air Conditioning: What to Check Before Summer Hits

Tech Tip of the Week | Encks Auto Repair By Paul Enck | Call: 727-822-1

Start With the Simple Stuff

As temperatures climb, drivers are turning their AC on for the first time in months. If it is working fine, there is no need to have it serviced. But if it is not cooling the way it should, there is a simple check you can do before assuming the worst.

“If your AC is working, there’s no reason to have it serviced. If it’s not working, there’s one of the simplest things you can do — look for these little black caps on these lines.”

— Paul Enck, Encks Auto Repair

The First Thing to Check

AC systems have two service ports — a high side and a low side — each covered by a small black cap. These caps protect the Schrader valves underneath, which are similar to the valves on a tire.

Here is what to do:

• Locate the black caps on the AC lines under the hood
• Remove the caps and inspect them
• Look for oil residue inside the cap — this is a sign the valve underneath is leaking
• Listen for a hissing sound when the cap is removed — another indicator of a leaking valve

“Remove these caps. If you get a little noise or if you see oil inside the cap, this valve is leaking.”

— Paul Enck, Encks Auto Repair

A Real Example From the Shop

Paul walks through a vehicle that came in with a completely non-functional AC system. The diagnosis pointed to something straightforward and inexpensive.

“This AC system did not work. It was a matter of replacing the filler valves on the high and low side, filling it with refrigerant after pulling the system down. The customer spent about 180 dollars. Now his AC is working and he’s good to go for summer.”

— Paul Enck, Encks Auto Repair

A repair that could have been assumed to be a major AC job turned out to be a valve replacement and a recharge — a modest fix that got the system back up and running before summer.

What the Repair Involves

When leaking valves are the culprit, the repair process typically goes like this:

• Replace the Schrader valves on the high and low side service ports
• Pull the system down — a vacuum is applied to remove any moisture and air from the system
• Recharge with refrigerant — the correct amount of refrigerant is added to bring the system back to full capacity

This is not a DIY repair due to refrigerant handling regulations, but it is one of the more affordable AC fixes available.

Pro Tip: Checking the black caps on your AC lines takes less than a minute and costs nothing. If you see oil in the cap or hear any noise when removing it, that is your starting point before spending money on a more involved diagnosis.

Frequently Asked Questions

1. If my AC is working fine, do I need to have it serviced?

No. As Paul says directly — if your AC is cooling properly, there is no need to service it. Save the expense and address it only if performance drops.

2. What does oil inside the AC cap mean?

It means the Schrader valve underneath is leaking. AC systems use oil to lubricate internal components, and when a valve leaks, that oil escapes and collects inside the cap. It is a clear sign the valve needs to be replaced.

3. Can I replace the AC Schrader valves myself?

The valves themselves are inexpensive and the removal is straightforward, but recharging the system with refrigerant requires certified equipment and handling. Most drivers are better off having a shop handle the full repair.

4. How much does an AC recharge typically cost?

A basic recharge generally runs between 100 and 200 dollars depending on the shop and the vehicle. As Paul’s example shows, when valve replacements are included, the total came to around 180 dollars — still a very manageable repair compared to more involved AC work.

5. What are the most common reasons an AC system stops working?

Low or depleted refrigerant is the most common cause, often due to a slow leak somewhere in the system. Other causes include a failed compressor, a clogged expansion valve, a faulty blower motor, or leaking Schrader valves as Paul describes in this Tech Tip.

6. How do I know if my AC is low on refrigerant?

The most obvious sign is that the air blowing from the vents is not as cold as it used to be, or it blows cool but never gets truly cold. The system may also run longer than usual trying to reach the set temperature.

7. Is it normal for AC systems to lose refrigerant over time?

A small amount of loss over many years is normal due to natural permeation through hoses and seals. However, significant or rapid refrigerant loss always indicates a leak somewhere in the system that needs to be found and repaired before simply recharging.

8. What does pulling the system down mean?

Pulling the system down refers to applying a vacuum to the AC system before recharging it. This removes any air and moisture that may have entered the system. Moisture inside an AC system can freeze at the expansion valve and cause blockages, so this step is essential before adding fresh refrigerant.

9. Can a leaking Schrader valve cause the entire AC system to stop working?

Yes. If the valve leaks enough refrigerant out of the system over time, the pressure drops to the point where the compressor will not engage — leaving you with no cold air at all. That is exactly what happened in the vehicle Paul describes in this Tech Tip.

10. How often should I have my AC system inspected?

There is no fixed interval for AC inspection the way there is for oil changes or tire rotations. The best approach is to test your AC at the start of warm weather each year. If it cools properly, leave it alone. If performance has dropped or it is not working at all, start with the simple checks Paul outlines before moving to a full diagnosis.