A/C problem 5.4 V8

Reply Subscribe

Thread Tools

Search this Thread

Aug 7, 2022 | 09:36 AM

Thegreatone0414

Thread Starter

6th Gear

Joined: Aug 2022

Posts: 6

Likes: 0

A/C problem 5.4 V8

Hey guys I just made my profile here because I inherited my dads excursion after his passing. I got the a/c system fixed recently but for sone reason can’t get it to blow cold at idle. It blows great as I’m driving and get nice and chilly but if I’m sitting still in park it stops cooling. The compressor is new (it’s a bit noisy though). The evaporator new. The orifice tube is new as well and the dryer as well. It is mechanically working fine now just not blowing cold unless it’s moving. The shoot tends to think it has to do with a leaking vacuum reservoir. I think it’s a dirty condenser since this truck sat in my dads yard for a year due to his declining health. Please any help would be awesome

Aug 7, 2022 | 10:16 AM

pirate4x4_camo

FTE Remembers

Joined: Apr 2011

Posts: 8,259

Likes: 346

From: Northern California

AC warm at ideal causes.

fan clutch
stretched belt
weak tensioner
missing air damn pieces

could be a dirty condenser but that typically causes warm at all speeds.

Aug 7, 2022 | 11:53 AM

Thegreatone0414

Thread Starter

6th Gear

Joined: Aug 2022

Posts: 6

Likes: 0

Well the compressor started knocking really bad now I almost thought the truck threw a lifter or piston but nope once I turn a/c off knock goes a way

Aug 7, 2022 | 12:53 PM

projectSHO89

Hotshot

Joined: Jan 2004

Posts: 19,768

Likes: 1,082

From: St Louis

Quote:

Originally Posted by Thegreatone0414

Well the compressor started knocking really bad now I almost thought the truck threw a lifter or piston but nope once I turn a/c off knock goes a way

Couple of things it might be:

Low charge. At a certain low charge level, the compressor can get very noisy when it doesn't have enough refrigerant to pump.
Clutch hub is failing.
Internal compressor failure.

Don't overlook all the other stuff that pirate mentioned.

Aug 7, 2022 | 04:11 PM

pirate4x4_camo

FTE Remembers

Joined: Apr 2011

Posts: 8,259

Likes: 346

From: Northern California

Quote:

Originally Posted by Thegreatone0414

Well the compressor started knocking really bad now I almost thought the truck threw a lifter or piston but nope once I turn a/c off knock goes a way

Belt slipping makes a racket that sounds just like a knock.

check the belt wear indicator on your tensioner.

Aug 7, 2022 | 06:34 PM

Thegreatone0414

Thread Starter

6th Gear

Joined: Aug 2022

Posts: 6

Likes: 0

The truck has brand new belt, tensioner and idler pulley. So I’m really leaning towards the compressor. Any way to know for sure as a backyard mechanic?

Aug 7, 2022 | 07:43 PM

pirate4x4_camo

FTE Remembers

Joined: Apr 2011

Posts: 8,259

Likes: 346

From: Northern California

Quote:

Originally Posted by Thegreatone0414

The truck has brand new belt, tensioner and idler pulley. So I’m really leaning towards the compressor. Any way to know for sure as a backyard mechanic?

did the noise start when the belt was changed ?

its easy to get the wrong length belt because the ford part numbers are the same.
the difference is the subfix which often gets ignored.

the Pk number looks like a 990 on the 5.4 but i am not to hip on 5.4 variations.

for example though on the 7.3 there are different alternator pulley options which change the belt and i have been given a 8620jk instead of the 8620aa, it fits but isn’t tight enough and causes what sounds like rod knock from the front of the compressor but is really the belt slipping when the AC is turned on.

edit, 5.4 is a ford 8620ea