Help me diagnose ac problem
Thread Starter
|
New User
Joined: Sep 2019
Posts: 3
Likes: 0
Help me diagnose ac problem
I have a 2002 Eddie Bauer expedition. The main ac blows warm air. The rear blows cold. At idle low side 37 high side 190 ambient temp 90 degrees. Small line on evaporator coming out of firewall sweating and cold large line warm. Could problem be a blend door?
Laughing Gas
Joined: Feb 2003
Posts: 877
Likes: 27
From: South Florida
Very likely. Also have an assistant cycle the temperature selector control from cold to hot and back and you watch the hot water valve linkage to make sure the hot water valve is cycling closed and open in conjunction with temperature selection. But if the back is getting cold and the front is stuck on hot, the front blend door actuator is a very likely suspect.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
It's a bit low on refrigerant.
A blend door issue won't cause "Small line on evaporator coming out of firewall sweating and cold large line warm". The large line (output) is warm because there isn't enough refrigerant.
A blend door issue won't cause "Small line on evaporator coming out of firewall sweating and cold large line warm". The large line (output) is warm because there isn't enough refrigerant.
Thread Starter
|
New User
Joined: Sep 2019
Posts: 3
Likes: 0
I failed to mention that while front vents register about 85 degrees while the rear are about 60. Shouldn't front vents get to 60 as well if it was due to low refrigerant. I agree that it's a bit low though. Where is the front blend door actuator located?
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
If the refrigeration system isn't functioning, the air coming out of the vents will be ambient plus a little. So, if it was 75 degrees when you checked outlet temps, that's about right. If it was 85 and the system was working just a bit, the temps would be about 80. It all depends.
Quit fixating on the blend door, get the refrigeration system working. If the blend door was malfunctioning, you' likely be complying about the outlet temps being stuck on HOT (like 100+ temps) or you'd have absolutely no control over outlet temps.
Quit fixating on the blend door, get the refrigeration system working. If the blend door was malfunctioning, you' likely be complying about the outlet temps being stuck on HOT (like 100+ temps) or you'd have absolutely no control over outlet temps.
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 738
From: Isanti, MN
Just out of curiosity, how would a low refrigerant condition cause this? It's the condenser's job to cool hot refrigerant coming out of the compressor, so wouldn't a hot output line to the evaporator reflect more on airflow through the condenser?
Trending Topics
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
He has a cold evaporator inlet but a warm outlet line from the evaporator. The condenser's lines were not under discussion. Since you mentioned it, it's the job of the condenser to condense the high pressure gas into a high pressure liquid, a process that removes heat from the refrigerant.
Within the evaporator, the opposite happens. The refrigerant essentially "boils" (evaporates) absorbing heat in the process. If there isn't enough refrigerant available to boil in the evaporator to utilize the whole core, only a proportionately lesser amount of heat will be absorbed from the cabin air passing through the core's fins.
Bottom line is that, in this person's case, there isn't enough liquid refrigerant entering the evaporator to absorb the amount of heat in the air passing through the evaporator's fins. That means either the overall level of refrigerant in the system is too low or, perhaps, the metering orifice is restricted (clogged).
Think of the system as a "BTU Transporter". It moves thermal energy (heat) from one point (the cabin) to another (outside).
Within the evaporator, the opposite happens. The refrigerant essentially "boils" (evaporates) absorbing heat in the process. If there isn't enough refrigerant available to boil in the evaporator to utilize the whole core, only a proportionately lesser amount of heat will be absorbed from the cabin air passing through the core's fins.
Bottom line is that, in this person's case, there isn't enough liquid refrigerant entering the evaporator to absorb the amount of heat in the air passing through the evaporator's fins. That means either the overall level of refrigerant in the system is too low or, perhaps, the metering orifice is restricted (clogged).
Think of the system as a "BTU Transporter". It moves thermal energy (heat) from one point (the cabin) to another (outside).
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post
Dendroica
Cooling, Heating, Ventilation & A/C
5
Jun 21, 2013 06:14 PM
RITTERBY
1997 - 2006 Expedition & Navigator
6
Sep 12, 2009 08:35 PM
Mythreefords
Cooling, Heating, Ventilation & A/C
3
Oct 26, 2005 05:21 PM