AC Oil Leak and Coolant - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eyebuzz · 08-12-2011, 08:11 PM

Hi All,

About two weeks ago some low viscosity oil started leaking out on the passenger side floor (didn't seem like motor oil) - had a little bit of coolant smell - but I collected it in a container and it was all oil that leaked out over the coming days - no coolant.

Question 1: from what I've read seems like AC refrigerant (it has AC -- but not working since I've owned her)...Does AC refrigerant have oil in it? - is that what that oil is?

Question 2: Just today started blowing steam out the heater vents with the distinct coolant smell - OK - so I've got a leak/my heater core is going, etc...but what's the connection with the oil? I couldn't quite tell what was leaking out today...but seemed much more coolant based and not oil.

Are these two events just a coincidence - or is this a classic symptom of something?

Thanks, TT

PanelDeland · 08-12-2011, 08:23 PM

Are you sure it's oil and not Ethlyne/Glycol.It sometimes has the "slick" feel of oil.

eyebuzz · 08-12-2011, 11:17 PM

Thanks for the reply. If you mean coolant - no was definitely oil - but thinner than motor oil. - I collected it in a glass container so I could see enough of the stuff - I know what you mean though about coolant feeling slick...

piecesparts · 08-12-2011, 11:22 PM

Where under the truck is the leaking material collecting? Yes, the A/C has oil in it. The smell of the oil would not smell like engine coolant, though.

Refrigerant oil is thinner than engine oil, but it is also a dehydrated oil when it is in the system, so it will collect moisture once it leaks out.

eyebuzz · 08-12-2011, 11:49 PM

The oil was right on the passenger floor-right out of the plastic box. Today it was also leaking coolant - as well as blowing steam out the heat vents (didn't get to collect any today but by the speed it was dripping out I could tell) - so my questions is it common for both the AC and heater hose or core to fail together...(maybe they run though the same core??). I'm going to break into it all tomorrow..just wanted to get some ideas first.

Wrenchbender Ret · 08-13-2011, 12:08 AM

The cores are separate but they are close together. It is very unusual for oil to leak out of the evaporater like that. It usually leaks very little & when its under pressure. But evidently the bottom is corrodedb out of your evap. core.

ls1nova71 · 08-13-2011, 03:15 AM

If your evaporator is leaking refrigerant oil, I seriously doubt it would make it into the cab. The evaporator is on the engine side of the firewall and any oil would leak out the drain on the bottom of the A/C box where the condensation drips out of. Even if that were plugged up, it would take more oil than the system has in it to fill up and start running out of the inside box. My guess is what others have said, it's coolant you collected, it can look like oil when it seeps out of a heater core or radiator.
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eyebuzz · 08-13-2011, 09:56 AM

Thanks all - I'm going to break into it today for more details. It is definitely oil and not coolant - of course my first fear was a blown head gasket and the oil and coolant were mixed...but when I collected the oil in a glass container it was all oil (got about 3 or 4 oz. of the stuff).

Anyway, one last question - IF it is refrigerant oil that is leaking, does this mean that I don't have to worry about messing with the AC system - meaning, is the refrigerant pretty much leaked out? - I'm guessing yes, but just want to check first.

piecesparts · 08-13-2011, 11:06 AM

Quote:

Originally Posted by eyebuzz

Thanks all - I'm going to break into it today for more details. It is definitely oil and not coolant - of course my first fear was a blown head gasket and the oil and coolant were mixed...but when I collected the oil in a glass container it was all oil (got about 3 or 4 oz. of the stuff).

Anyway, one last question - IF it is refrigerant oil that is leaking, does this mean that I don't have to worry about messing with the AC system - meaning, is the refrigerant pretty much leaked out? - I'm guessing yes, but just want to check first.

The odds are that if you have oil leaking out, then you still have some refrigerant pushing the oil out of the system. You can handle this in many ways. first is the legal way of having the refrigerant reclaimed and have someone strip it out with a vacuum pump. Second would be for you to remove the schrader valve core ont he system and let it blow down by itself. HMMMM wonder if you are really killing the ozone???? Just think--they are still doing this on the other side of the border in our neighboring countries. Those are the two simplest choices. However most of the freon is gone, is a fair guess. When you turn the A/C on while the truck is running, does the compressor clutch engage and run? If so, the system has a large amount of freon left, because the compressor works off of the pressure switch on the accumulator. If it is low on freon, the switch will not make up.

Wrenchbender Ret · 08-13-2011, 04:02 PM

Maybe the oil is leaking from the pressure gauge & running down the edge of the dash.

eyebuzz · 08-23-2011, 09:42 AM

Thanks for all the advice - quick recap - so I went ahead and replaced the heater core - when opening the box up it was really hard to tell why the refrigerant oil would be leaking inside - the AC box (from the inside) on the engine side dips down below the fire wall opening - way down, and it was NOT full of oil - the only thing I can think is it was squirting out through the fire wall opening under pressure. Since the AC wasn't working before I'm just leaving that job for a later day.

As a side note for those looking to replace your heater core - go for it - pretty easy job - time more than skill. One thing is I needed to replace the gasket between the heater box and the fire wall - can be ordered from the usual sources. I also replace the S shaped heat pipe below the dash and bought some new ducts for defrost (didn't have them before) - took the radio out while I was there - but never got around to testing it - just put it back in. Best, TT

08-12-2011, 08:11 PM	#1
eyebuzz Licensed driver Join Date: Jun 2010 Location: Tarrytown, NY Posts: 161	AC Oil Leak and Coolant Hi All, About two weeks ago some low viscosity oil started leaking out on the passenger side floor (didn't seem like motor oil) - had a little bit of coolant smell - but I collected it in a container and it was all oil that leaked out over the coming days - no coolant. Question 1: from what I've read seems like AC refrigerant (it has AC -- but not working since I've owned her)...Does AC refrigerant have oil in it? - is that what that oil is? Question 2: Just today started blowing steam out the heater vents with the distinct coolant smell - OK - so I've got a leak/my heater core is going, etc...but what's the connection with the oil? I couldn't quite tell what was leaking out today...but seemed much more coolant based and not oil. Are these two events just a coincidence - or is this a classic symptom of something? Thanks, TT

08-12-2011, 08:23 PM	#2
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: AC Oil Leak and Coolant Are you sure it's oil and not Ethlyne/Glycol.It sometimes has the "slick" feel of oil. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

08-12-2011, 11:17 PM	#3
eyebuzz Licensed driver Join Date: Jun 2010 Location: Tarrytown, NY Posts: 161	Re: AC Oil Leak and Coolant Thanks for the reply. If you mean coolant - no was definitely oil - but thinner than motor oil. - I collected it in a glass container so I could see enough of the stuff - I know what you mean though about coolant feeling slick... Last edited by eyebuzz; 08-12-2011 at 11:19 PM. Reason: additional info added

08-12-2011, 11:22 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: AC Oil Leak and Coolant Where under the truck is the leaking material collecting? Yes, the A/C has oil in it. The smell of the oil would not smell like engine coolant, though. Refrigerant oil is thinner than engine oil, but it is also a dehydrated oil when it is in the system, so it will collect moisture once it leaks out. __________________ Frank

08-12-2011, 11:49 PM	#5
eyebuzz Licensed driver Join Date: Jun 2010 Location: Tarrytown, NY Posts: 161	Re: AC Oil Leak and Coolant The oil was right on the passenger floor-right out of the plastic box. Today it was also leaking coolant - as well as blowing steam out the heat vents (didn't get to collect any today but by the speed it was dripping out I could tell) - so my questions is it common for both the AC and heater hose or core to fail together...(maybe they run though the same core??). I'm going to break into it all tomorrow..just wanted to get some ideas first.

08-13-2011, 12:08 AM	#6
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: AC Oil Leak and Coolant The cores are separate but they are close together. It is very unusual for oil to leak out of the evaporater like that. It usually leaks very little & when its under pressure. But evidently the bottom is corrodedb out of your evap. core.

08-13-2011, 03:15 AM	#7
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,118	Re: AC Oil Leak and Coolant If your evaporator is leaking refrigerant oil, I seriously doubt it would make it into the cab. The evaporator is on the engine side of the firewall and any oil would leak out the drain on the bottom of the A/C box where the condensation drips out of. Even if that were plugged up, it would take more oil than the system has in it to fill up and start running out of the inside box. My guess is what others have said, it's coolant you collected, it can look like oil when it seeps out of a heater core or radiator. Posted via Mobile Device

08-13-2011, 09:56 AM	#8
eyebuzz Licensed driver Join Date: Jun 2010 Location: Tarrytown, NY Posts: 161	Re: AC Oil Leak and Coolant Thanks all - I'm going to break into it today for more details. It is definitely oil and not coolant - of course my first fear was a blown head gasket and the oil and coolant were mixed...but when I collected the oil in a glass container it was all oil (got about 3 or 4 oz. of the stuff). Anyway, one last question - IF it is refrigerant oil that is leaking, does this mean that I don't have to worry about messing with the AC system - meaning, is the refrigerant pretty much leaked out? - I'm guessing yes, but just want to check first.

08-13-2011, 04:02 PM	#10
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: AC Oil Leak and Coolant Maybe the oil is leaking from the pressure gauge & running down the edge of the dash.

08-23-2011, 09:42 AM	#11
eyebuzz Licensed driver Join Date: Jun 2010 Location: Tarrytown, NY Posts: 161	Re: AC Oil Leak and Coolant Thanks for all the advice - quick recap - so I went ahead and replaced the heater core - when opening the box up it was really hard to tell why the refrigerant oil would be leaking inside - the AC box (from the inside) on the engine side dips down below the fire wall opening - way down, and it was NOT full of oil - the only thing I can think is it was squirting out through the fire wall opening under pressure. Since the AC wasn't working before I'm just leaving that job for a later day. As a side note for those looking to replace your heater core - go for it - pretty easy job - time more than skill. One thing is I needed to replace the gasket between the heater box and the fire wall - can be ordered from the usual sources. I also replace the S shaped heat pipe below the dash and bought some new ducts for defrost (didn't have them before) - took the radio out while I was there - but never got around to testing it - just put it back in. Best, TT



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