“For I am not ashamed of the gospel.” — Romans 1:16
klein cooling ac university header graphic link

CALL NOW
Skip to main content
A/C University
Table of Contents
< All Topics
Print

My AC Guy Says My Compressor Is Pulling Too Many Amps

Your AC guy says:

“Your compressor is pulling too many amps.”

That can absolutely be a problem.

But before we sentence the compressor:

How many amps is it actually pulling?

And:

What are we comparing that number to?

RLA and LRA Are Not the Same Thing

Look at the data plate on your outdoor unit or compressor and you’ll see numbers such as:

RLA — Rated Load Amps

and

LRA — Locked Rotor Amps

Those numbers mean very different things.

LRA is associated with the extremely high current a motor can draw when the rotor isn’t turning—such as during startup or a locked-rotor condition.

RLA is used in relation to the compressor’s normal operating characteristics and equipment design.

So if somebody sees a big number for a fraction of a second when the compressor starts:

That doesn’t automatically mean the compressor is failing.

Starting current and running current aren’t the same thing.

What About While It’s Running?

Now we’re interested.

If the compressor is operating and drawing unusually high current, we want to know why.

Possible contributors can include:

  • high outdoor conditions
  • high condensing pressure
  • dirty condenser coil
  • condenser airflow problems
  • voltage problems
  • refrigerant conditions
  • electrical problems
  • mechanical compressor problems

That’s why:

“It’s pulling high amps.”

may be a useful observation.

But it’s not automatically:

“You need a compressor.”

Can You Just Compare Running Amps to the Nameplate?

The nameplate gives us useful information, but compressor amperage changes with operating conditions.

A compressor working on a brutal Florida afternoon isn’t necessarily going to draw exactly what it did on a mild morning.

We want to understand:

Voltage.
Pressures.
Temperatures.
Outdoor conditions.
Condenser airflow.

Then the amp reading starts telling a story.

What Should You Ask?

Ask:

“What amperage did the compressor measure?”

Then:

“What should it be under these conditions?”

And if the answer is that it’s unusually high:

“What’s causing it?”

That’s the important part.

The Klein Answer

Your compressor absolutely can draw excessive current.

And that can be an important warning sign.

But one large number appearing on a meter doesn’t automatically condemn it.

First determine whether we’re looking at:

normal starting current, abnormal starting current, or excessive running current.

Then figure out why.

Because:

“Your compressor pulled a lot of amps.”

is a measurement.

“Your compressor is dying.”

requires a little more evidence.

The clamp meter gets a vote.

It doesn’t get the whole jury.